Article

Metschnikowia noctiluminum sp. nov., Metschnikowia corniflorae sp. nov., and Candida chrysomelidarum sp. nov., isolated from green lacewings and beetles

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Abstract

Fourteen yeast isolates belonging to the Metschnikowia clade were isolated from the digestive tracts of lacewings (Neuroptera: Chrysopidae), soldier beetles and leaf beetles (Coleoptera: Cantharidae and Chrysomelidae), and a caddisfly (Trichoptera: Hydropsychidae). The insect hosts were associated with sugary substances of plants, a typical habitat for yeasts in this clade. Based on DNA sequence comparisons and phenetic characters, the yeasts were identified as Candida picachoensis, Candida pimensis, and four undescribed taxa. Among the undescribed taxa, three yeasts were distinguished from one another and from other described taxa by nucleotide differences in the ribosomal DNA repeat, which were sufficient to consider them as new species. Two of the novel yeast species are described as Metschnikowia noctiluminum (NRRL Y-27753(T)) and M. cornifloraespp. nov. (NRRL Y-27750(T)) based in part on production of needle-shaped ascospores, which are found in most Metschnikowia species. Sexual reproduction was not observed in the third new yeast, Candida chrysomelidarumsp. nov. (NRRL Y-27749(T)). A fourth isolate, NRRL Y-27752, was not significantly distinct from Metschnikowia viticola and Candida kofuensis to be described as a new species. Phylogenetic analysis of the D1/D2 loop sequences placed M. noctiluminum within the M. viticola clade, while C. chrysomelidarum was a sister taxon of Candida rancensis. Metschnikowia corniflorae was phylogenetically distinct from other new species and fell outside of the large-spored Metschnikowia group.

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... Multiple studies investigating various insects in other locations (shown in Figure 2) indicated an even geographical distribution of S. cerevisiae. The budding yeast has not been isolated from ants, lacewings, termites, mites, and mosquitoes (the group "others" in Figure 2), which were, however, poorly investigated (two species in different locations at most) (Carreiro et al., 1997;Lachance et al., 2003;Suh et al., 2005;Nguyen et al., 2006;Steyn et al., 2016;Siavoshi et al., 2018). Similarly, S. cerevisiae has not been found in butterflies (n = 11 species in different locations) and moths (n = 4) Witzgall et al., 2012;Ravenscraft et al., 2018). ...
... Similarly, S. cerevisiae has not been found in butterflies (n = 11 species in different locations) and moths (n = 4) Witzgall et al., 2012;Ravenscraft et al., 2018). Interestingly, only the 0.03% of beetles, which have been widely investigated (n = 236), bear S. cerevisiae (Kurtzman and Robnett, 1998;Lachance et al., 2001aLachance et al., ,b, 2006Six, 2003;Suh and Blackwell, 2004, Suh et al., 2005Delalibera et al., 2005;Nguyen et al., 2006;Rosa et al., 2007;Rivera et al., 2009;de Vega et al., 2012;Hui et al., 2012;Toki et al., 2012;Freitas et al., 2013;Kaltenpoth and Steiger, 2013;Ninomiya et al., 2013;Urbina et al., 2013;Cline et al., 2014;Ren et al., 2014Ren et al., , 2015Liu et al., 2016;Tanahashi and Hawes, 2016;Wang et al., 2016;Briones-Roblero et al., 2017;Chai et al., 2019). Similarly, bees only accidentally bear S. cerevisiae, with only 1 occurrence over 21 reported cases (Sandhu and Waraich, 1985;Lachance et al., 2003;Rosa et al., 2003;Daniel et al., 2013;Charron et al., 2014;Saksinchai et al., 2015). ...
... Similarly, bees only accidentally bear S. cerevisiae, with only 1 occurrence over 21 reported cases (Sandhu and Waraich, 1985;Lachance et al., 2003;Rosa et al., 2003;Daniel et al., 2013;Charron et al., 2014;Saksinchai et al., 2015). Conversely, S. cerevisiae has been found in a large portion of investigated flies, fruit flies, honey-bees, and wasps (29, 57, 20, and 71%, respectively) (Phaff and Knapp, 1956;Batra et al., 1973;Sandhu and Waraich, 1985;Morais et al., 1993Morais et al., , 1994Rosa et al., 1994;Lachance et al., 1995Lachance et al., , 2003Lachance et al., , 2006Suh et al., 2005;Nguyen et al., 2006Nguyen et al., , 2007Basukriadi et al., 2010;Goddard et al., 2010;Chandler et al., 2012;de Vega et al., 2012;Hamby et al., 2012;Stefanini et al., 2012;Freitas et al., 2013;Buser et al., 2014;Charron et al., 2014;Lam and Howell, 2015;Saksinchai et al., 2015;Batista et al., 2017;Deutscher et al., 2017;Jimenez et al., 2017;Piper et al., 2017;Quan and Eisen, 2018;Siavoshi et al., 2018;dos Santos et al., 2019;Meriggi et al., 2019;Park et al., 2019). A few possible scenarios could explain the higher occurrence of S. cerevisiae in these groups of insects: (i) they are more prone to visit human-related environments, such as wineries and vineyards, that are likely to host higher amounts of S. cerevisiae cells, (ii) they are more attracted by substrates inhabited by the budding yeast compared to other insects, (iii) diet and physical-chemical intestine conditions facilitate the housing of S. cerevisiae. ...
Article
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Over the last few years, an increasing number of studies have reported the existence of an association between the budding yeast Saccharomyces cerevisiae and insects. The discovery of this relationship has called into question the hypothesis that S. cerevisiae is unable to survive in nature and that the presence of S. cerevisiae strains in natural specimens is the result of contamination from human-related environments. S. cerevisiae cells benefit from this association as they find in the insect intestine a shelter, but also a place where they can reproduce themselves through mating, the latter being an event otherwise rarely observed in natural environments. On the other hand, insects also take advantage in hosting S. cerevisiae as they rely on yeasts as nutriment to properly develop, to localize suitable food, and to enhance their immune system. Despite the relevance of this relationship on both yeast and insect ecology, we are still far from completely appreciating its extent and effects. It has been shown that other yeasts are able to colonize only one or a few insect species. Is it the same for S. cerevisiae cells or is this yeast able to associate with any insect? Similarly, is this association geographically or topographically limited in areas characterized by specific physical features? With this review, we recapitulate the nature of the S. cerevisiae-insect association, disclose its extent in terms of geographical distribution and species involved, and present YeastFinder, a cured online database providing a collection of information on this topic.
... In some insects, symbiotic bacteria remain associated throughout their life cycle supplying essential nutrients to their host (Bridges, 1981). Several microbes like yeasts have also been recorded from insect guts, particularly those feeding on fruiting bodies, flowers and nectar (Lachance & Bowles, 2002;Nguyen, Suh, Erbil, & Blackwell, 2006;Suh, Gibson, & Blackwell, 2004). However, little progress has been made to further elucidate the role of microbial symbionts in biotic fitness attributes of natural enemies after the prominent work of Hagen, Tassan, and Sawall (1970) on Chrysoperla carnea. ...
... It is being increasingly realised that the gut and other organs of many insect species harbour bacteria and fungi in a symbiotic relationship and some of these microbes can be tracked to sources in the environment like wood flowers and nectars (Bignell, 1984;Kurtzman, 2001;Lachance et al., 2001;Nguyen et al., 2006;Suh et al., 2004). Several microbes have symbiotic relationship with its host by supplying nutrients (Douglas, 1998) or even provide the host with ability to overcome parasitism by wasp parasitoids (Oliver, Russell, Moran, & Hunter, 2003). ...
... Several species of the genus Metschnikowi have been isolated from nectar, honeydew, pollen, flowers, and fruits mainly from Chrysoperla spp. (Hagen et al., 1970;Nguyen et al., 2006;Suh et al., 2004). Many studies have shown that yeasts provide nutrients like essential amino acids which influence faster growth and development in insects (Vega & Dowd, 2005). ...
Article
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Four bacterial and one-yeast species, cultured and identified as Stenotrophomonas maltophilia, Acinetobacter sp., Pseudomonas sp. and Ochrobactrum sp. and the yeast as Metschnikowia reukaufii, were isolated from the internal organs of four collections of field-sourced egg parasitoid, Trichogramma chilonis, obtained as parasitized H. armigera eggs. Bacteria were identified through 16 rRNA amplification and sequencing. The single species of yeast was identified through Internal Transcribed Spacer sequences. A single bacterial species could be isolated from each of the four T. chilonis collections, however all four T. chilonis collections yielded the yeast, Metschnikowia reukaufii. In order to study the influence of the association of each of the bacterial species and the yeast, microbe-free laboratory bred populations of T. chilonis were fed with the individual cultures and fitness parameters as parasitisation vigour and female-bias were studied in T. chilonis over 10 generations. T. chilonis fed with either Stenotrophomonas maltophilia or Acinetobacter sp. and Pseudomonas sp., showed a mean percent increase in female ratio of 26.2, 30 and 30.3% and mean percent parasitisation of H. armigera eggs significantly increased by 38, 32.2 and 31.3%, respectively. However, T. chilonis fed with Acinetobacter sp did not positively influence the two T. chilonis fitness factors. The ubiquitous yeast, Metschnikowia reukaufii, which could be isolated from all four collections of T. chilonis, could significantly increase both female count and percent parasitism ratio by 22 and 65%, respectively. This study has opened the possibility of modulating the parasitisation fitness of laboratory bred T. chilonis, prior to field release, using microbes associated with them in the wild.
... When they were discovered many of these yeasts represented novel species, some placed in entirely new clades (e.g. Suh et al 2004bSuh et al , 2006). Most of the previous isolations, however, have been restricted to a small number of specific insect groups, primarily beetles (Coleoptera), various bees and wasps (Hymenoptera), flies (Diptera) and lacewings (Neuroptera). ...
... Therefore we attempted to isolate yeasts from the gut and surface of insects in 13 orders (48 families), excluding those that feed directly on fungi or flowers. Although previously we discussed some yeasts associated with lacewings (Suh et al 2004a, Nguyen et al 2006) here we focus on additional isolates from other families of Neuroptera, including those that are associated with other insects in a more comprehensive study. ...
... Individual insects were separated in clean containers lined with dampened filter paper and held 3 d. Methods for yeast isolation were detailed by Nguyen et al (2006) and Suh et al (2004b). Briefly, starved insects were submerged in 95% ethanol 2-3 min to disinfect the surface; this step was followed by a wash with 0.7% saline solution, and the wash liquid was plated on acidified YM agar (Difco YM broth, 2% plain agar, adjusted to pH 3.5 with HCl) to serve as negative control. ...
Article
Full-text available
Ascomycete yeasts are found commonly in the guts of basidioma-feeding beetles but little is known about their occurrence in the gut of other insects. In this study we isolated 95 yeasts from the gut of adult insects in five neuropteran families (Neuroptera: Corydalidae, Chrysopidae, Ascalaphidae, Mantispidae and Hemerobiidae) and a roach (Blattodea: Blattidae). Based on DNA sequence comparisons and other taxonomic characteristics, they were identified as more than 15 species of Saccharomycetes as well as occasional Cryptococcus-like basidiomycete yeasts. Yeast species such as Lachancea fermentati, Lachancea thermotolerans and Hanseniaspora vineae were isolated repeatedly from the gut of three species of corydalids, suggesting a close association of these species and their insect hosts. Among the yeasts isolated in this study 12 were identified as five novel Candida species that occurred in three phylogenetically distinct clades. Molecular phylogenetic analyses showed that Candida chauliodes sp. nov. (NRRL Y-27909T) and Candida corydali sp. nov. (NRRL Y-27910T) were sister taxa in the Candida albicans/ Lodderomyces elongisporus clade. Candida dosseyi sp. nov. (NRRL Y-27950T) and Candida blattae sp. nov. (NRRL Y-27698T) were sister taxa in the Candida intermedia clade. Candida ascalaphidarum sp. nov. (NRRL Y-27908T) fell on a basal branch in a clade containing Candida membranifaciens and many other insect-associated species. Descriptions of these novel yeast species are provided as well as discussion of their ecology in relation to their insect hosts.
... For instance, in addition to the fungus Cladosporium spp., the yeast Candida spp. have been linked to bark and rove beetles [22][23][24][25][26]. Oomycetes contain numerous plant pathogens responsible for considerable damage to the environment as well [17,[27][28][29][30]. ...
... Candida spp. are natural biocontrols agents of fruit and vegetable pests [128][129][130], and are also associated with bark beetles [22,[24][25][26]. Following species subtraction, our results showed the presence of Candida michaelii only in the samples baited with the C6C8 semiochemical, which primarily attracts long-horned beetles, but the addition of ethanol makes it attractive to bark beetles as well. ...
Article
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Studying the means of dispersal of plant pathogens is crucial to better understand the dynamic interactions involved in plant infections. On one hand, entomologists rely mostly on both traditional molecular methods and morphological characteristics, to identify pests. On the other hand, high-throughput sequencing (HTS) is becoming the go-to avenue for scientists studying phytopathogens. These organisms sometimes infect plants, together with insects. Considering the growing number of exotic insect introductions in Canada, forest pest-management efforts would benefit from the development of a high-throughput strategy to investigate the phytopathogenic fungal and oomycete species interacting with wood-boring insects. We recycled formerly discarded preservative fluids from the Canadian Food Inspection Agency annual survey using insect traps and analysed more than one hundred samples originating from across Canada. Using the Ion Torrent Personal Genome Machine (PGM) HTS technology and fusion primers, we performed metabarcoding to screen unwanted fungi and oomycetes species, including Phytophthora spp. Community profiling was conducted on the four different wood-boring, insect-attracting semiochemicals; although the preservative (contained ethanol) also attracted other insects. Phytopathogenic fungi (e.g., Leptographium spp. and Meria laricis in the pine sawyer semiochemical) and oomycetes (mainly Peronospora spp. and Pythium aff. hypogynum in the General Longhorn semiochemical), solely associated with one of the four types of semiochemicals, were detected. This project demonstrated that the insect traps’ semiochemical microbiome represents a new and powerful matrix for screening phytopathogens. Compared to traditional diagnostic techniques, the fluids allowed for a faster and higher throughput assessment of the biodiversity contained within. Additionally, minimal modifications to this approach would allow it to be used in other phytopathology fields.
... For instance, in addition to the fungus Cladosporium spp., the yeast Candida spp. have been linked to bark and rove beetles [22][23][24][25][26]. Oomycetes contain numerous plant pathogens responsible for considerable damage to the environment as well [17,[27][28][29][30]. ...
... Candida spp. are natural biocontrols agents of fruit and vegetable pests [128][129][130], and are also associated with bark beetles [22,[24][25][26]. Following species subtraction, our results showed the presence of Candida michaelii only in the samples baited with the C6C8 semiochemical, which primarily attracts long-horned beetles, but the addition of ethanol makes it attractive to bark beetles as well. ...
Preprint
Understanding ecological interactions is a key in managing phytopathology. Although entomologists rely mostly on both traditional molecular methods and morphological characteristics to identify pests, next-generation sequencing is becoming the go-to avenue for scientists studying fungal and oomycete phytopathogens. These organisms sometimes infect plants together with insects. There are many relationships yet to be discovered and much to learn about how these organisms interact with one another. Considering the growing number of exotic insect introductions in Canada, a high-throughput strategy for screening those insects is already implemented by the Canadian Food Inspection Agency (CFIA). However, no plan is deployed to investigate the phytopathogenic fungal and oomycete species interacting with insects. Metagenomics analysis was performed on the preservation fluids from CFIA’s insect traps across Canada. Using the Ion Torrent PGM technology and fusion primers for multiplexing and indexing, community profiling was conducted on the different semiochemicals used in the insect traps and the various areas where these traps were placed. Internal transcribed spacer 1 (fungi and oomycetes) and adenosine triphosphate synthase subunit 9-nicotinamide adenine dinucleotide dehydrogenase subunit 9 spacer amplicons were generated. Although direct links between organisms could not be established, moderately phytopathogenic fungi (e.g., Leptographium spp. and Meria laricis) and oomycetes (mainly Peronospora spp. and Pythium spp.) unique to every type of semiochemical were discovered. The entomopathogenic yeast Candida michaelii was also detected. This project demonstrated our ability to screen for unwanted species faster and at a higher scale and throughput than traditional pathogen diagnostic techniques. Additionally, minimal modifications to this approach would allow it to be used in other phytopathology fields.
... The insect gut is known to harbor diverse microbiota that often perform beneficial role, though some are known to have opportunistically harmful role (Bignell, 1984;Kaufman and Klug, 1991;Dillon and Dillon, 2004;Bernays and Klein, 2002;Tagami et al., 2006;Bourtzis and Miller, 2003;Broderick et al., 2006). Several yeasts have been recorded in insects, mainly those feeding on fruiting bodies, flowers and nectar (Lachance and Bowles, 2002;Suh et al., 2004;Nguyen et al., 2006). Ferrari et al., (2006) reported host-associated differentiation in divergent microbiota isolated from pea aphid. ...
... The microbiota generally varies with feeding habits, like sap feeders (sucking pests) to termites (wood or cellulose feeder) to insects which feed on foliage or tissue / fruit borers (Rizzi et al., 2013). Another group of insects, parasitoids, which essentially are surviving on its host and as a free-living adults feed on fruits, flowers and nectar, acquire generally yeast and sometimes bacterial microbiota (Suh et al., 2004;Nguyen et al., 2006;Srinatha et al, 2015). In insects, microbiota-insect host-plant-host interactions are formed by different factors because insects lack a 'classical' adaptive protected system (McFall-Ngai, 2007). ...
Article
Full-text available
Host-insect and host-plant associated differentiation of genetically divergent microbiota were recorded from economically important egg parasitoid collected from 26 locations in India, Trichogramma chilonis constituted 86.8% of the populations collected. It was recorded from 14 host-insects, 14 different crops and weed plants from 12 states. Nine species of yeast were recorded from parasitoid from 5 host-insects with Wickerhamomyces anamalus was isolated from 36.4% samples and highest numbers were recorded from parasitoid collected on sugarcane. Bacillus cereus, Pseudomonas sp. and Stenotrophomonas maltophilia from T. chilonis constitute 64.3% of bacterial diversity based on their 16S rDNA sequences. For taxonomic identification using 16s rDNA and ITS sequences, we performed taxonomic classification of total 33 ITS isolates against UNITE Fungal ITS database and assigned taxonomy hierarchy to the sequences. Also, a total of 13 isolates 16s rDNA sequences were taxonomically assigned against RDP 16s rDNA database using RDP Naive Bayesian rRNA Classifier Version 2.1. Most of the species are correctly identified in the respective species members with high confidence threshold value support.
... The insect gut is known to harbor diverse microbiota that often perform beneficial role, though some are known to have opportunistically harmful role (Bignell, 1984;Kaufman and Klug, 1991;Dillon and Dillon, 2004;Bernays and Klein, 2002;Tagami et al., 2006;Bourtzis and Miller, 2003;Broderick et al., 2006). Several yeasts have been recorded in insects, mainly those feeding on fruiting bodies, flowers and nectar (Lachance and Bowles, 2002;Suh et al., 2004;Nguyen et al., 2006). Ferrari et al., (2006) reported host-associated differentiation in divergent microbiota isolated from pea aphid. ...
... The microbiota generally varies with feeding habits, like sap feeders (sucking pests) to termites (wood or cellulose feeder) to insects which feed on foliage or tissue / fruit borers (Rizzi et al., 2013). Another group of insects, parasitoids, which essentially are surviving on its host and as a free-living adults feed on fruits, flowers and nectar, acquire generally yeast and sometimes bacterial microbiota (Suh et al., 2004;Nguyen et al., 2006;Srinatha et al, 2015). In insects, microbiota-insect host-plant-host interactions are formed by different factors because insects lack a 'classical' adaptive protected system (McFall-Ngai, 2007). ...
Article
Full-text available
Host-insect and host-plant associated differentiation of genetically divergent microbiota were recorded from economically important egg parasitoid collected from 26 locations in India, Trichogramma chilonis constituted 86.8% of the populations collected. It was recorded from 14 host-insects, 14 different crops and weed plants from 12 states. Nine species of yeast were recorded from parasitoid from 5 host-insects with Wickerhamomyces anamalus was isolated from 36.4% samples and highest numbers were recorded from parasitoid collected on sugarcane. Bacillus cereus, Pseudomonas sp. and Stenotrophomonas maltophilia from T. chilonis constitute 64.3% of bacterial diversity based on their 16S rDNA sequences. For taxonomic identification using 16s rDNA and ITS sequences, we performed taxonomic classification of total 33 ITS isolates against UNITE Fungal ITS database and assigned taxonomy hierarchy to the sequences. Also, a total of 13 isolates 16s rDNA sequences were taxonomically assigned against RDP 16s rDNA database using RDP Naive Bayesian rRNA Classifier Version 2.1. Most of the species are correctly identified in the respective species members with high confidence threshold value support.
... In addition to beetles, another example of close associations of yeasts with insects comes from Metschnikowia chrysoperlae and the related species, Candida picachoensis and Candida pimensis, associated only with the green lacewings , Chrysoperla spp. (Suh et al. 2004a; Nguyen et al. 2006). During our study of beetle gut yeasts, we discovered another hidden yeast clade related to Candida kruisii. ...
... The methods and conditions for DNA extraction, PCR, and electrophoresis for microsatellite-primed PCR (MSP-PCR) were according to the methods of Sampaio et al. (2001) and Nguyen et al. (2006). Two primers, (GTG) 5 and (GAG) 5 , were used for the analysis. ...
Article
Yeasts similar to Candida kruisii were isolated repeatedly from the digestive tracts of basidioma-feeding beetles, especially nitidulids inhabiting and feeding on a variety of agarics in the southeastern USA and Barro Colorado Island, Panama. Based on the identical sequences of the D1/D2 domains of the LSU rRNA gene (rDNA) and host beetle information, the isolates were grouped into 19 genotypes which varied from C. kruisii by up to 38 nucleotide differences in the D1/D2 region. Phylogenetic analysis of rDNA sequences and phenotypic traits placed the isolates in C. kruisii and in nine undescribed taxa. The new species and type strains are designated as Candida pallodes (NRRL Y-27653(T)), C. tritomae (NRRL Y-27650(T)), C. panamensis (NRRL Y-27657(T)), C. lycoperdinae (NRRL Y-27658(T)), C. atbi (NRRL Y-27651(T)), C. barrocoloradensis (NRRL Y-27934(T)), C. aglyptinia (NRRL Y-27935(T)), C. stri (NRRL Y-48063(T)), and C. gatunensis (NRRL Y-48064(T)). A phylogeny based on analysis of a combined database of sequences of SSU and LSU rDNA and the ITS region showed that the nine new species formed a novel sister clade to C. kruisii that was strongly supported by bootstrap analysis. Candida pallodes, C. tritomae, C. panamensis, and C. lycoperdinae formed one subclade, while C. atbi, C. barrocoloradensis, C. aglyptinia, C. stri, and C. gatunensis formed a second distinct subclade within the larger clade. Candida pallodes and C. atbi showed a strong host specificity to beetle species in the genus Pallodes (Coleoptera: Nitidulidae) collected from a variety of agarics. On the other hand, C. panamensis, C. tritomae, and C. lycoperdinae were associated with several unrelated beetles in Erotylidae, Scarabaeidae, Tenebrionidae, and Curculionidae as well as Lycoperdina ferruginea (Nitidulidae). Candida pallodes, C. tritomae, C. lycoperdinae, and C. atbi have been isolated repeatedly in the USA, while the other five new species have been found only at Barro Colorado Island, Panama.
... Yeasts have been isolated frequently from the gut or surface of insects that feed on a variety of materials, including basidiomycete fruiting bodies, woody substrates, ephemeral flowers and nectar exudates (Kurtzman 2001, Lachance and Bowles 2002, 2004, Lachance et al 2001a, b, 2005, Suh et al 2003, 2004a, b, 2005, Suh and Blackwell 2004, Pimentel et al 2005). When they were discovered many of these yeasts represented novel species, some placed in entirely new clades (e.g.Suh et al 2004bSuh et al , 2006). Most of the previous isolations, however, have been restricted to a small number of specific insect groups, primarily beetles (Coleoptera), various bees and wasps (Hymenoptera), flies (Diptera) and lacewings (Neuroptera). ...
... Individual insects were separated in clean containers lined with dampened filter paper and held 3 d. Methods for yeast isolation were detailed byNguyen et al (2006)and Suh et al (2004b). Briefly, starved insects were submerged in 95% ethanol 2–3 min to disinfect the surface; this step was followed by a wash with 0.7% saline solution, and the wash liquid was plated on acidified YM agar (Difco YM broth, 2% plain agar, adjusted to pH 3.5 with HCl) to serve as negative control. ...
Article
Full-text available
Ascomycete yeasts are found commonly in the guts of basidioma-feeding beetles but little is known about their occurrence in the gut of other insects. In this study we isolated 95 yeasts from the gut of adult insects in five neuropteran families (Neuroptera: Corydalidae, Chrysopidae, Ascalaphidae, Mantispidae and Hemerobiidae) and a roach (Blattodea: Blattidae). Based on DNA sequence comparisons and other taxonomic characteristics, they were identified as more than 15 species of Saccharomycetes as well as occasional Cryptococcus-like basidiomycete yeasts. Yeast species such as Lachancea fermentati, Lachancea thermotolerans and Hanseniaspora vineae were isolated repeatedly from the gut of three species of corydalids, suggesting a close association of these species and their insect hosts. Among the yeasts isolated in this study 12 were identified as five novel Candida species that occurred in three phylogenetically distinct clades. Molecular phylogenetic analyses showed that Candida chauliodes sp. nov. (NRRL Y-27909T) and Candida corydali sp. nov. (NRRL Y-27910T) were sister taxa in the Candida albicans/ Lodderomyces elongisporus clade. Candida dosseyi sp. nov. (NRRL Y-27950T) and Candida blattae sp. nov. (NRRL Y-27698T) were sister taxa in the Candida intermedia clade. Candida ascalaphidarum sp. nov. (NRRL Y-27908T) fell on a basal branch in a clade containing Candida membranifaciens and many other insect-associated species. Descriptions of these novel yeast species are provided as well as discussion of their ecology in relation to their insect hosts.
... typographi infected specimens of I. sexdentatus were macerated and dispersed on malt extract agar and Sabouraud dextrose agar in Petri dishes. YM agar was used as a first step selective medium (Nguyen et al., 2006). Samples were incubated at 22°C (±1°C) for seven days. ...
... Several Metschnikowia spp. were found on the surface of insects or in their intestine (Nguyen et al., 2006;Lachance, 2011). Ingestion of M. bicuspidata by Daphnia magna in water has been reported (Ebert et al., 2000), as has transfer of unharmed spores to Daphnia dentifera via ingestion of fish faeces (Duffy, 2009). ...
Article
Ips sexdentatus (Six-spined engraver beetle) from Austria and Poland were dissected and examined for the presence of pathogens. Specimens collected in Austria were found to contain the ascomycetous fungus Metschnikowia cf. typographi. Infection rates ranged from 3.6% to 26.8% at different collection sites. M. cf. typographi infected midguts were investigated by histological, ultrastructural and molecular techniques. Extraordinary ultrastructural details are shown, such as ascospores with bilateral flattened flanks resembling alar rims at both sides of their attenuating tube-like ends. These have not yet been described in other yeast species. Molecular investigations showed a close phylogenetic relationship to the fungi Metschnikowia agaves and Candida wancherniae. Presence of the entomopathogenic fungus Beauveria bassiana found in Austria was confirmed both morphologically and molecularly. The eugregarine Gregarina typographi was diagnosed most frequently. Infection rates of all I. sexdentatus specimens ranged from 21.4% to 71.9% in Austria and 54.1% to 68.8% in Poland. Other entomopathogenic protists, bacteria, or viruses were not detected.
... In this regard the chrysopid predators are also found to harbor many endosymbiotic yeasts like symbionts in adults which may provide essential amino acids that are normally absent in their diet (Hagen andTassan, 1966, 1972). Hagen et al. (1970) identified the yeasts Torulopsis sp. in Chrysopa carnea, Nguyen et al. (2007) isolated five novel Candida sp. from Neuropteran, some of the yeasts like Metschnikowia noctiluminum, Candida picachoensis and C. pimensis were obtained from gut of adult lacewings (Woolfolk et al., 2003;Suh et al., 2004;Nguyen et al., 2006). Chrysopid predators harbor bacteria in their mid gut region which degrades the digestive residues (Mc-Dunnough, 1909;Spiegler, 1962;Jepp, 1984). ...
... Chrysopids are found to have association with variety of micro flora namely Torulopsis sp. (Hagen et al., 1970(Hagen et al., , 1972; Candida multigemmis (Buhagiar) Meyer and Yarrow; T. multigemmis (Johnson, 1982); Metschnikowia chrysoperla, C. picachoensis and C. pimensis (Suh, 2004;Gibson et al., 2005); M. pulcherrima (Woolfolk et (Nguyen et al., 2006). Kodamaea ohmere was isolated from gut of female Corydalus cornutus (Neuroptera) (Nguyen et al., 2007) found M. pulcherrima was predominant yeast found in the alimentary canal of Chr. ...
Article
Full-text available
Common green lacewing, Chrysoperla zastrowi sillemi is one of the important biological control agents and is used effectively to manage various insect pests. Chrysopid predators are found to harbor many endosymbiotic yeasts and bacteria. Keeping this in view, a study on the distribution of yeast and bacteria in the adult diverticulum and larval gut was conducted using transmission electron microscopy (TEM) and molecular techniques. TEM showed the presence of a load of bacterial cells towards the periphery of inner side of the epithelial lining and the dividing bacterial cells in the larval gut. Numerous oval and kidney shaped yeast fauna were found to be distributed within the lumen and diverticular folds of the diverticulum of adult. Our study reveals the presence and distribution of yeast and bacterial cells from the adult diverticulum and gut of larva. Microbial isolates were identified by sequencing 16S rRNA gene for bacteria and ITS region of yeast including partial rRNA genes ITS-1 and partial 5.8S rRNA gene for yeast, respectively which revealed the presence of yeast isolates namely Kodamaea ohmeri, Torulaspora delbrueckii, Wickerhamomyces anomalus and bacterial isolates namely: Enterobacter hormaechei, E. cloacae and Enterobacter sp. as most common from adult and larvae, respectively.
... Many insects from plant materials, such as flower-visiting beetles and green lacewings, were associated with species of Metschnikowia and related asexual yeasts (e.g. Lachance et al., 1998 Lachance et al., , 2005 Lachance & Bowles, 2004; Suh et al., 2004a; Nguyen et al., 2006a). Starmerella species were associated with several types of bees ( Teixeira et al., 2003), and Wickerhamiella species were often associated with Drosophila spp. ...
Article
Yeasts related to Candida albicans were isolated from the digestive tracts of beetles in eight families and various orders of insects such as earwigs, crickets, and roaches, most of which were caught at light traps or in a few cases directly from plant materials. Based on comparisons of DNA sequences and other taxonomic characteristics, a total of 41 isolates were identified as Candida orthopsilosis, Candida pseudorhagii, Candida maltosa, Candida parapsilosis, Candida tropicalis, Candida neerlandica, Lodderomyces elongisporus, and seven new Candida species. The new species and type strains are designated as Candida gigantensis NRRL Y-27736T, Candida bohiensis NRRL Y-27737T, Candida alai NRRL Y-27739T, Candida buenavistaensis NRRL Y-27734T, Candida frijolesensis NRRL Y-48060T, Candida labiduridarum NRRL Y-27940T, and Candida tetrigidarum NRRL Y-48142T. A phylogeny based on SSU and LSU rRNA gene sequences indicated that most of the new species were closely related to members of the C. albicans/L. elongisporus clade, such as C. albicans, Candida dulbliniensis, C. neerlandica, Candida chauliodes, and Candida corydali. Candida alai was placed near this clade, but no closely related sister taxon was identified. The ecology of the insect-associated yeasts is discussed and compared with the results from other studies.
... Also similar to our results, these previous studies isolated primarily those bacterial taxa known for symbiotic associations with animals and plants [67,68], rather than those groups commonly isolated from the soil or other sources. Sometimes these gut symbionts of insects pervade throughout an insect population, especially when the insect has physiological adaptations in their digestive systems that house bacterial symbionts (e.g., gastric caecae or structurally complex alimentary canals) [1,61,69,70,71]. Only a few of the bacteria were found in more than 50% of the symbiotic H. pensylvanicus population, notably Spiroplasma montanense (tRF 472; Mollicutes), Alphaproteobacteria (tRF 440, closest genetic matches were Wolbachia pipientis and Ehrlichia shimanesis, whose genetic similarities to the clones were approximately 87%), and a Gammaproteobacteria (tRF 421; closest genetic matches were Pantoea dispersa UQ68J and Enterobacter aerogenes, whose genetic similarities to the clones were between 96.2–97.4%) ...
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Obligate bacterial symbionts alter the diets of host animals in numerous ways, but the ecological roles of facultative bacterial residents that colonize insect guts remain unclear. Carabid beetles are a common group of beneficial insects appreciated for their ability to consume insect prey and seeds, but the contributions of microbes to diet diversification in this and similar groups of facultative granivores are largely unknown. Using 16S rRNA gene clone libraries and terminal restriction fragment (tRF) length polymorphism analyses of these genes, we examined the bacterial communities within the guts of facultatively granivorous, adult Harpalus pensylvanicus (Carabidae), fed one of five dietary treatments: 1) an untreated Field population, 2) Seeds with antibiotics (seeds were from Chenopodium album), 3) Seeds without antibiotics, 4) Prey with antibiotics (prey were Acheta domesticus eggs), and 5) Prey without antibiotics. The number of seeds and prey consumed by each beetle were recorded following treatment. Harpalus pensylvanicus possessed a fairly simple gut community of approximately 3-4 bacterial operational taxonomic units (OTU) per beetle that were affiliated with the Gammaproteobacteria, Bacilli, Alphaproteobacteria, and Mollicutes. Bacterial communities of the host varied among the diet and antibiotic treatments. The field population and beetles fed seeds without antibiotics had the closest matching bacterial communities, and the communities in the beetles fed antibiotics were more closely related to each other than to those of the beetles that did not receive antibiotics. Antibiotics reduced and altered the bacterial communities found in the beetle guts. Moreover, beetles fed antibiotics ate fewer seeds, and those beetles that harbored the bacterium Enterococcus faecalis consumed more seeds on average than those lacking this symbiont. We conclude that the relationships between the bacterium E. faecalis and this factultative granivore's ability to consume seeds merit further investigation, and that facultative associations with symbiotic bacteria have important implications for the nutritional ecology of their hosts.
... hawaiiana within group 3 whereas the D1/D2 LSU rRNA gene sequence phylogeny (Lachance, 2011b) inferred a close relationship with members of group 4. Indeed, here we reported for the first time a basal position of M. drosophilae and C. torresii within group 3 (Fig. 1). Another point of disagreement is the derived position of M. corniflorae (group 4) within Metschnikowia found in the present study whereas a basal position with respect to the LSM clade is inferred when analyzing the D1/D2 LSU rRNA gene (Nguyen et al., 2006). In contrast, the LSM clade is mostly recovered as a strongly supported monophyletic group regardless of genetic marker and analytical method of phylogenetic inference (Lachance, 2011b; Lachance et al., 2001). ...
... Lacewings are well known for their symbiotic association with yeasts, bacteria and filamentous fungi. Yeasts of the genera Candida and Metschnikowia are commonly reported in lacewings (Suh et al., 2004;Woolfolk and Inglis, 2004;Nguyen et al., 2006) and although the specific role of yeasts is poorly understood, they are thought to provide the host with a source of nutrients. More than 25 taxa of bacteria have been isolated from the alimentary canal of adult C. rufilabris and both larval and adult C. carnea. ...
Article
Lacewing larvae are generalist predators that are commercially available for aphid control on a variety of crops in both Europe and North America. Although lacewings are known for their symbiotic association with yeasts and bacteria, there are few reports of microsporidia in these natural enemies. An undescribed microsporidium was found in Chrysoperla carnea (Stephens) during the routine examination of specimens that were obtained from a commercial insectary for biological pest control. The objective of this study was to describe the pathogen by means of ultrastructure, molecular characterization and tissue pathology. All stages of the microsporidium were diplokaryotic and developed in direct contact with the host cell cytoplasm. Merogony and sporogony were not observed. Mature spores measured 3.49 ± 0.10 x 1.52 ± 0.05 μm and had an isofilar polar filament with 8-10 coils that were frequently arranged in a single row, although double rows were also observed. Spores contained a lamellar polaroplast and a relatively small and inconspicuous polar vacuole was observed in the posterior region of about half of the spores that were examined. Tubular structures, similar in appearance to those in Nosema granulosis were observed in both sporonts and in spores. A cluster of small tubules was also observed in the posterior region of some spores. Microsporidian spores were observed in cells of the proventriculus, diverticulum and in epithelial cells of the posterior midgut. The Malpighian tubules, ilium, and rectum were heavily infected. Spores were also observed in the fat body, peripheral region of the ganglia, within and between the flight muscles, and beneath the cuticle. Although the tissues adjacent to the ovaries were heavily infected, microsporidian spores were not observed within the developing eggs. Pathogen transmission was not studied directly because it was difficult to maintain microsporidia-infected C. carnea in the laboratory. The presence of microsporidian spores in the alimentary canal suggests that the pathogen is transmitted per os and horizontal transmission may occur when infected larvae or adults are cannibalized by uninfected larvae. Molecular analysis of the microsporidian genome showed that the pathogen described in this study was 99% similar to Nosema bombycis, N. furnacalis, N. granulosis and N spodopterae. Based on information gained during this study, we propose that the microsporidium in C. carnea be given the name Nosema chrysoperlae sp. nov.
... Metschnikowia species are widely distributed in terrestrial habitats and are often found associated with a variety of substrates, including insects, flowers, fruits, and many types of plant materials (Hui et al. 2013;Lachance et al. 2001a, b;Peter et al. 2005;Sipiczki 2014;Xue et al. 2006). These species are thought to be transported to new niches by pollinators, including bees, drosophilids, and beetles (Guzmán et al. 2013;Lachance et al. 2001a, b;Lachance and Bowles 2002;Lachance et al. 2003b;Nguyen et al. 2006). Insects often play an important role in flower-associated yeast communities, as terrestrial flowering plants and their associated insects markedly impact genetic diversification within the Metschnikowia genus (Guzmán et al. 2013). ...
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Four yeast strains (RIFY 10001T, RIFY 10002, RIFY 10003, and RIFY 10004) were isolated from flowers growing in fields of mustard and broad beans in Japan. Ascospore formation was not observed. Sequence analysis of the D1/D2 domain of the large subunit ribosomal RNA (LSU rRNA) gene of the four strains indicated that they belong to the genus Metschnikowia and are closely related to Metschnikowia hawaiiana strain CBS 9146T and Metschnikowia orientalis strain CBS 10331T. The D1/D2 domain of the LSU rRNA gene and internal transcribed spacer regions of strain RIFY 10001T were 85.7% identical to those of M. hawaiiana strain CBS 9146T. All four strains were distinguished from the M. hawaiiana strain CBS 9146T by their inability to ferment glucose. Hence, these four strains are novel species and were named as Metschnikowia miensis (holotype: RIFY 10001T; isotypes: NBRC 112445T = CBS 14749T).
... T.delbrueckii naturally colonized a wide range of anthropized habitats. This species is also frequently isolated from natural environments, ranging from soils [47], to plants [48], fruits [49] and insects [50,51]. Finally, this species, although not considered to be a human pathogen, is occasionally found as a clinical isolate [52] where it is usually referred as Candida colliculosa, the anamorphic form of T. delbrueckii [53]. ...
Article
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The yeast Torulaspora delbrueckii is associated with several human activities including oenology, bakery, distillery, dairy industry, etc. In addition to its biotechnological applications, T. delbrueckii is frequently isolated in natural environments (plant, soil, insect). T. delbrueckii is thus a remarkable ubiquitous yeast species with both wild and anthropic habitats, and appears to be a perfect yeast model to search for evidence of human domestication. For that purpose, we developed eight microsatellite markers that were used for the genotyping of 110 strains from various substrates and geographical origins. Microsatellite analysis showed four genetic clusters: two groups contained most nature strains from Old World and Americas respectively, and two clusters were associated with winemaking and other bioprocesses. Analysis of molecular variance (AMOVA) confirmed that human activities significantly shaped the genetic variability of T. delbrueckii species. Natural isolates are differentiated on the basis of geographical localisation, as expected for wild population. The domestication of T. delbrueckii probably dates back to the Roman Empire for winemaking (∼1900 years ago), and to the Neolithic era for bioprocesses (∼4000 years ago). Microsatellite analysis also provided valuable data regarding the life-cycle of the species, suggesting a mostly diploid homothallic life. In addition to population genetics and ecological studies, the microsatellite tool will be particularly useful for further biotechnological development of T. delbrueckii strains for winemaking and other bioprocesses.
... The communities consist mostly of yeasts in four clades centered around the genera Metschnikowia , Kodamaea, Wickerhamiella and Starmerella. Several new species of the genus Candida associated with flowers and insects, described recently, include Candida hawaiiana and Candida kipukae (Lachance et al., 2003), Candida picachoensis and Candida pimensis (Suh et al., 2004), Candida chrysomelidarum (Nguyen et al., 2006), Candida tibetensis and Candida linzhiensis (Wu & Bai, 2006). During the survey of yeast species associated with flowers, about 150 yeast strains were isolated from Rawatbhata town (25 : 10 : 34 N, 15 : 49 : 51 E), Rajasthan state of India. ...
Article
Two novel yeast strains designated as 16Q1 and 16Q3 were isolated from flowers of the Ruellia species of the Acanthaceae family. The D1/D2 domain and ITS sequences of these two strains were identical. Sequence analysis of the D1/D2 domain of large-subunit rRNA gene indicated their relationship to species of the Candida haemulonii cluster. However, they differ from C. haemulonii by 14% nucleotide sequence divergence, from Candida pseudohaemulonii by 16.1% and from C. haemulonii type II by 16.5%. These strains also differ in 18 physiological tests from the type strain of C. haemulonii, and 12 and 16 tests, respectively, from C. pseudohaemulonii and C. haemulonii type II. They also differ from C. haemulonii and other related species by more than 13% sequence divergence in the internal transcribed spacer region. In the SSU rRNA gene sequences, strain 16Q1 differs by 1.7% nucleotide divergence from C. haemulonii. Sporulation was not observed in pure or mixed cultures on several media examined. All these data support the assignment of these strains to a novel species; we have named them as Candida ruelliae sp. nov., and designate strain 16Q1(T)=MTCC 7739(T)=CBS10815(T) as type strain of the novel species.
... Metschnikowia yeasts are commonly found on fruits, flowers and in nectar (Ethiraj et al., 1980;Manson et al., 2007;de Vega et al., 2012;Kaewwichian et al., 2012), where they encounter insects (Lachance et al., 2005;Nguyen et al., 2006;de Vega et al., 2012). So far, 39 Metschnikowia species are known to be associated with flower-visiting insects (Kaewwichian et al., 2012;Guzmán et al., 2013). ...
Article
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Associations between yeasts and insect herbivores are widespread, and these inter-kingdom interactions play a crucial role in yeast and insect ecology and evolution. We report a survey of insect attraction to live yeast from a community ecology perspective. In the summer of 2013 we screened live yeast cultures of Metschnikowia pulcherrima, M. andauensis, M. hawaiiensis, M. lopburiensis, and Cryptococcus tephrensis in an organic apple orchard. More than 3,000 arthropods from 3 classes, 15 orders, and 93 species were trapped; ca. 79% of the trapped specimens were dipterans, of which 43% were hoverflies (Syrphidae), followed by Sarcophagidae, Phoridae, Lauxaniidae, Cecidomyidae, Drosophilidae, and Chironomidae. Traps baited with M. pulcherrima, M. andauensis, and C. tephrensis captured typically 2.4 times more specimens than control traps; traps baited with M. pulcherrima, M. hawaiiensis, M. andauensis, M. lopburiensis and C. tephrensis were more species-rich than unbaited control traps. We conclude that traps baited with live yeasts of the genera Metschnikowia and Cryprococcus are effective attractants and therefore of potential value for pest control. Yeast-based monitoring or attract-and-kill techniques could target pest insects or enhance the assemblage of beneficial insects. Manipulation of insect behavior through live yeast cultures should be further explored for the development of novel plant protection techniques.
... Yeasts have been isolated frequently from the gut or surface of insects that feed on a variety of materials, including basidiomycete fruiting bodies, woody substrates, ephemeral flowers and nectar exudates (Kurtzman 2001, Lachance et al. 2001a, b, 2005, Rosa et al. 2003, Suh et al. 2003, 2004b, 2005a, b, Teixeira et al. 2003Suh & Blackwell 2004, 2005, Pimentel et al. 2005, Nguyen et al. 2006. Yeasts have been also described as endosymbionts in mosquito populations, lacewings, beetles and homoptera (Ganter 2006, Urubschurov & Janczyk 2011. ...
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This work aimed to evaluate for the first time in Egypt the biodiversity of mycobiota that inhabit the guts of three insect species collected from Assiut Governorate. 50 adult insect samples (28 worker honey bees, 11 black beetles and 11 red palm weevils) were analyzed. 68 species and three varieties were recovered of which 49 species and 2 varieties were filamentous fungi and 19 species + one variety were yeasts. The number of taxa recovered from red-palm weevils and honey bees was almost equal, while lower number was isolated from beetles. However, a higher number of yeast species was obtained from the gut of red-palm weevils than those obtained from honey bees or black beetles. Some filamentous species were recovered from the guts of the three insect species (Aspergillus niger, A. parasiticus, A. terreus, Cladosporium cladosporioides, Penicillium chrysogenum), while others were reported from one or two insect species. However, none of yeast species was regularly recovered from the three insect guts, but two insect species may share the same yeast species in their guts. Other yeast species were restrictedly isolated from guts of one insect species. Some gut samples were fungi-free. To our knowledge, some of the isolated yeast species are being reported here for the first time from insect guts. On the other hand, ITS sequence data from several strains did not match well with those of known described species, and are probably new species.
... As already reported in the literature, the species Aureobasidium pullulans was identified in this study (Pardo et al., 1989; van Keulen et al., 2003). Discrimination of several very close species of the genus Metschnikowia (Kurtzman and Droby, 2001; Nguyen et al., 2006; Suh et al., 2004) is not currently possible with this method. By pyrosequencing method used in this study, no identification at species level is possible. ...
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The efficiency of the FT-IR technique for studying the inter- and intra biodiversity of cultivable non-Saccharomyces yeasts (NS) present in different must samples was examined. In first, the capacity of the technique FT-IR to study the global diversity of a given sample was compared to the pyrosequencing method, used as a reference technique. Seven different genera (Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Issatchenkia, Metschnikowia and Pichia) were identified by FT-IR and also by pyrosequencing. Thirty-eight other genera were identified by pyrosequencing, but together they represented less than 6% of the average total population of 6 musts. Among the species identified, some of them present organoleptic potentials in winemaking, particularly Starmerella bacillaris (synonym Candidazemplinina). So in a second time, we evaluated the capacity of the FT-IR technique to discriminate the isolates of this species because few techniques were able to study intraspecific NS yeast biodiversity. The results obtained were validated by using a classic method as ITS sequencing. Biodiversity at strain level was high: 19 different strains were identified from 58 isolates. So, FT-IR spectroscopy seems to be an accurate and reliable method for identifying major genera present in the musts. The two biggest advantages of the FT-IR are the capacity to characterize intraspecific biodiversity of non-Saccharomyces yeasts and the possibility to discriminate a lot of strains.
Article
Information concerning molecular reidentification of the species of the rejected genus Chlamydozyma is generalized. The yeasts Chl. pulcherrima Wickerham (1964) and Chl. reukaufii Wickerham (1964) are shown to be sibling species of Metschnikowia pulcherrima Pitt et Miller (1968) and M. reukaufii Pitt et Miller (1968), respectively. Restoration of the species M. zygota (Wickerham) Fell at Hunter (1968) is proposed. The parasexual cycle and the prospects of its application for investigation of the Metschnikowia yeasts are discussed. Keywordsyeasts– Chlamydozyma, Metschnikowia –sibling species–DNA-DNA hybridization–molecular phylogeny–mating types–mitotic haploidization
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From comparisons of ITS1-5.8S-ITS2 and gene sequences for nuclear D1/D2 LSU rRNA, nuclear SSU (18S) rRNA, translation elongation factor 1-α (EF1-α) and RNA polymerase II subunit 2 (RPB2), the following four new ascosporogenous yeast species were resolved and are described as Metschnikowia anglica (NRRL Y-7298T [type strain], CBS 15342, MycoBank MB 823167), Metschnikowia leonuri (NRRL Y-6546T, CBS 15341, MB 823166), Metschnikowia peoriensis (NRRL Y-5942T, CBS 15345, MB 823164) and Metschnikowia rubicola (NRRL Y-6064T, CBS 15344, MB 823165). The following six species of Candida are members of the Metschnikowia clade and are proposed for transfer to Metschnikowia as new combinations: Candida chrysomelidarum (NRRL Y-27749T, CBS 9904, MB 823223), Candida gelsemii (NRRL Y-48212T, CBS 10509, MB 823192), Candida kofuensis (NRRL Y-27226T, CBS 8058, MB 823195), Candida picachoensis (NRRL Y-27607T, CBS 9804, MB 823197), Candida pimensis (NRRL Y-27619T, CBS 9805, MB 823205) and Candida rancensis (NRRL Y-48702T, CBS 8174, MB 823224). Candida fructus (NRRL Y-17072T, CBS 6380, MB 823206) is transferred to Clavispora as a new combination, and Candida musae is shown to be a synonym of C. fructus. Apparent multiple alleles for ITS, D1/D2, EF1-α and RPB2 were detected in strains of some species.
Chapter
Minute organisms, including yeasts with diverse physiological capabilities, make possible the existence of arthropods, especially insects, the most speciose group of organisms on Earth. The yeast growth form occurs throughout most of the fungal kingdom and is often associated with insects. Fungi and insects evolved together in the same habitats where casual associations certainly occurred early in their shared geological history and yeast attractants for insects developed over their lives together. Examples of their interactions range from accidental dispersal and the use of yeasts as food to obligate mutualisms described in this chapter. These include discussions of yeast-like symbionts, the use of the wasp gut for yeast outcrossing, extension of endophyte life cycles to include dispersal by insects, the advantage of yeasts in the diet of many insects such as blood-sucking dipterans, and the yeast-like germination of phoretic fungi in ephemeral habitats. Future studies of yeast–insect associations will continue to include species discovery but also approach theoretical questions of sexual and asexual reproduction, host specificity, host switching, advantages of horizontal and vertical dispersal, and studies that include entire interactive communities.
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A novel yeast species is described from 19 strains isolated from flowers and insects in three provinces of Cuba. The species is so far known only from Cuba. Characteristic asci and ascospores as well as phylogenetic analysis of the rDNA sequence place the novel species in the genus Metschnikowia. The novel species belongs to the New World subclade of large-spored species of Metschnikowia. Mating tests with other members of the subclade resulted in the formation of sterile asci without ascospores, showing that the Cuban strains represent a distinct biological species. Intraspecies matings lead to the production of fertile asci containing large needle-shaped ascospores. The novel species was further distinguished from its close relatives by rDNA sequences and PCR fingerprinting using primers derived from mini- and microsatellites. We propose the name Metschnikowia cubensis sp. nov. and designate MUCL 45753(T) (=CRGF 279(T) =CBS 10832(T), h(+)) as the type strain and MUCL 45751 (=CRGF 278 =CBS 10833, h(-)) as the allotype.
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This is the first report on the ascomycete Metschnikowia typographi from the adults and larvae of the great spruce bark beetle Dendroctonus micans in Turkey. In total, 910 of 1928 adults and 44 of 149 larvae investigated during the two years were infected by the pathogen. In a fresh smear the asci of the pathogen measure 18.5 +/- 2.05 microm (14.7-22.3) in length and 2.1 +/- 0.4 microm in width (n = 35). The ascospores are about 2 microm shorter than asci, having an average length of 16.4 +/- 1.5 microm (14.2-18.0). The total infection rate of D. micans was 47.2 %. The prevalence of M. typographi infections differed between localities and years. Different infection rates of male and female beetles of D. micans were not recognized.
Article
Seven yeast strains isolated from natural substrates of Thailand were found to represent two novel species of Candida, an ascomycetous anamorphic genus. Three strains, ST-233, ST-259 and ST-260, isolated from insect frass and plant leaves were found to represent a single novel species related to Metschnikowia agaves in a tree based on the D1/D2 domain sequences of the 26S rRNA genes. This species is clearly discriminated from M. agaves by the carbon assimilation patterns and required vitamins. The remaining four strains, ST-18, ST-261, ST-606 and ST-658, isolated from the fruit body of a mushroom, insect frass, decayed jack fruit and an unidentified flower, were found to represent a single species which is related to Candida corydali, a recently described insect-associated species, in a neighbor-joining tree based on the D1/D2 sequences. This species is clearly discriminated from C. corydali by the ability to assimilate propane-1,2-diol and the inability to assimilate glucono-delta-lactone. They are described as Candida wancherniae sp. nov. and Candida morakotiae sp. nov., respectively.
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The effects of different anthropogenic activities (vineyard, winery) on fungal populations from grape to wine were studied. To characterize these effects, it was necessary to access to the overall diversity of populations (pyrosequencing and spectroscopy FT-IR) but also to intra-specific diversity (FT-IR). Spectroscopy FT-IR has been validated for their ability to characterize the global population and to discriminate the strains for three species of non-Saccharomyces yeasts (NS). For the first time, it is shown that the grape berry is a limited source for NS yeasts while the winery seems to be a significant source; the air is an important vector for dissemination of these yeasts. In addition, persistence of NS yeast strains from year to year in the winery has been demonstrated. The studied anthropogenic activities modify the fungal diversity. Thus, lower biodiversity of grapes from organic modality was measured for the three vintages considered. The pressing / clarification step revises strongly fungal populations and the influence of the winery flora is confirmed. The addition of SO2 changes the population dynamics and favors the dominance of the species S. cerevisiae. The non-targeted chemical analysis shows, for the first time, that these wines can be distinguished at the end of the alcoholic fermentation (with or without SO2) depending on plant protection. Thus, the existence in wines of chemical and microbiological signatures associated with vineyard protection mode is highlighted.
Article
Two yeast morphotypes, BET 4(T) and BET 7, were isolated from the gut of click beetle Melanotus villosus. Click beetles were collected from the decaying timber within the woodlands of North Wyke Research, South West England, UK (latitude, 50°46'29″N; longitude, 3°55'23″W). Morphotype BET 7 was identified as Debaryomyces hansenii, and the other morphotype, BET 4(T), was found to differ from Priceomyces castillae and Priceomyces haplophilus, its closest phylogenetic neighbours, by 5.0% with respect to the nucleotide sequence of the D1/D2 domain of the large-subunit (LSU) rRNA gene, and by 8.0% with respect to the ribosomal internal-transcribed spacer (ITS) region. BET 4(T) also differ from P. castillae and P. haplophilus in a number of different phenotypic characteristics. Thus, based on the unique nucleotide sequences of its D1/D2 domain and ITS region, its physiological characteristics and an inability to sporulate, strain BET 4(T) is assigned the status of a new species of Candida, for which the name Candida northwykensis sp. nov., is proposed. The type strain is BET 4(T) (NCYC 3525(T) = CBS 11370(T)).
Article
Carpoglyphus lactis is a stored product mite infesting saccharide rich stored commodities including dried fruits, wine, beer, milk products, jams and honey. The association with microorganisms can improve the survival of mites on dried fruits. The microbial communities associated to C. lactis were studied in specimens originating from the packages of dried apricot, plums and figs and compared to the laboratory strain reared on house dust mite diet (HDMd). Clone libraries of bacterial 16S rRNA gene and fungal ITS region were constructed and analyzed by OTU approach. The 16S rRNA gene libraries differed among the compared diets. The sequences classified to the genera Leuconostoc, Elizabethkingia, Ewingella, Erwinia, Bacillus and Serratia were prevailing in mites sampled from the dried fruits. The ITS library showed smaller differences between the laboratory strain on HDMd and the isolates from dried fruits packages, with the exception of the mite strain from dried plums. The population growth was used as an indirect indicator of fitness and decreased in the order from yeast diet to HDMd, and dried fruits. The treatment and pretreatment of mites by antibiotics did not reveal the presence of antagonistic bacteria which might slow down the C. lactis population growth. The shifts of the microbial community in the gut of C. lactis were induced by the diet changes. The identified yeasts and bacteria are suggested as the main food source of stored product mites on dried fruits. The study describes the adaptation of C. lactis to feeding on dried fruits including the interaction with microorganisms. We also identified potentially pathogenic bacteria carried by the mites to dried fruits for human consumption. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Article
A novel yeast species is described based on three strains from the gut of wood-boring larvae collected in tree trunk of Ficus carica cultivated at the park near Nanyang, central China. Phylogenetic analysis based on sequences of the D1/D2 domains of the large subunit (LSU) rRNA gene showed that these strains occured in a separate clade genetically distinct from all known ascomycetous yeasts. In terms of pairwise sequence divergence, the novel strains differed by 15.3% divergence from Pichia terricola, and by 15.8% divergence from Pichia exigua and Candida rugopelliculosa in the D1/D2 domains. All three are ascomycetous yeasts in the Pichia clade. Unlike P. terricola, P. exigua and C. rugopelliculosa, this new species did not ferment glucose. The name Candida ficus sp. nov. is proposed to accommodate these highly divergent organisms with the type strain STN-8T (=CICC 1980T = CBS 12638T).
Article
Two strains of Wickerhamiella allomyrinae f.a., sp. nov. were isolated from the gut of Allomyrina dichotoma (Coleoptera: Scarabeidae) collected from the Baotianman National Nature Reserve, Nanyan, Henan Province, China. Sequence analyses of the D1/D2 domains of the large subunit (LSU) rRNA gene revealed that this new species was located in the Wickerhamiella clade (Saccharomycetes, Saccharomycetales), with the three described species of the genus Candida, namely, Candida musiphila, Candida spandovensis and Candida sergipensis, as its closest related species. The novel species differed from these three species by 9.3-9.8% sequence divergence (35-45 nucleotide substitutions) in the D1/D2 sequences. The species could also be distinguished from the closely related species, C. musiphila, C. spandovensis and C. sergipensis, by growth on vitamin-free medium and at 37 (o)C. The type strain is Wickerhamiella allomyrinae sp. nov. NYNU 13920(T) (= CICC 33031(T)= CBS 13167 (T)).
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The larva of codling moth Cydia pomonella (Tortricidae, Lepidoptera) is known as the worm in the apple, mining the fruit for food. We here show that codling moth larvae are closely associated with yeasts of the genus Metschnikowia. Yeast is an essential part of the larval diet and further promotes larval survival by reducing the incidence of fungal infestations in the apple. Larval feeding, on the other hand, enables yeast proliferation on unripe fruit. Chemical, physiological and behavioral analyses demonstrate that codling moth senses and responds to yeast aroma. Female moths are attracted to fermenting yeast and lay more eggs on yeast-inoculated than on yeast-free apples. An olfactory response to yeast volatiles strongly suggests a contributing role of yeast in host finding, in addition to plant volatiles. Codling moth is a widely studied insect of worldwide economic importance, and it is noteworthy that its association with yeasts has gone unnoticed. Tripartite relationships between moths, plants, and microorganisms may, accordingly, be more widespread than previously thought. It, therefore, is important to study the impact of microorganisms on host plant ecology and their contribution to the signals that mediate host plant finding and recognition. A better comprehension of host volatile signatures also will facilitate further development of semiochemicals for sustainable insect control.
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A yeast strain was isolated from the sputum sample of a leukaemia patient in the Spirito Santo Hospital of Pescara, Italy. The fungus produced a pigment that formed a reddish halo around colonies, and was identified and deposited as a Metschnikowia spp. (accession number IHEM 25107-GenBank accession number JQ921016) in the BCCM/IHEM collection of biomedical fungi and yeasts (Bruxelles, Belgium). Although the physiology of the strain was close to that of Metschnikowia sinensis, the D1/D2 sequence did not correspond to any previously described Metschnikowia species. Phylogeny of the genus Metschnikowia is complex and requires far more analysis. We present the first non-M. pulcherrima Metschnikowia spp. isolate recovered from a human, and emphasize the role of man as a transient carrier of environmental yeasts, the pathogenicity of which still needs to be defined.
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A novel anamorphic yeast species is described to accommodate three isolates recovered from the gut of three different wood-boring larvae collected in Henan, central China. On the basis of sequence analyses of the D1/D2 domains of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) regions, the three strains were assigned to be a novel species of the genus Wickerhamomyces, although the formation of ascospores was not observed. These strains also exhibited a number of distinct morphological and physiological characteristics that clearly differentiated them from Wickerhamomyces mucosus, Candida odintsovae and Wickerhamomyces rabaulensis, their closely related species. In view of the phenotypic differences and unique rDNA sequences, we considered that these three isolates represent a new species of the genus Wickerhamomyces, and therefore, a new species, Wickerhamomyces mori sp. nov. is proposed for this taxon. The type strain is NYNU1216T (= CICC 1983T = CBS 12678T).
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Three yeast strains designated as S44, XF1 and XF2, respectively, were isolated from Scolytus scheryrewi Semenov of apricot tree in Shule County, Xinjiang, China, and were demonstrated to be a new member of the genus Candida by sequence comparisons of 26S rRNA gene D1/D2 domain and internal transcribed spacer (ITS) region. BLASTn alignments on NCBI showed that the similarity of 26S rRNA gene sequences of S44 (type strain) to all sequences of other Candida yeasts was very low (≦93 %). The phylogenetic tree based on the 26S rRNA gene D1/D2 domain and ITS region sequences revealed that the strain S44 is closely related to C. blattae, C. dosseyi, C. pruni, C. asparagi, C. fructus and C. musae. However, the strain S44 is distinguished from these Candida species by the physiological characteristics. Moreover, the strain S44 formed typical pseudohyphae when grown on cornmeal agar at 25 °C for 7 days, but did not form ascospores in sporulation medium for 3–4 weeks. Therefore, the name Candida xinjiangensis is proposed for the novel species, with S44 (=KCTCT27747) as the type strain.
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There are very few natural enemies so maladapted as to rely on prey as their sole nutritional resource. The importance of non-prey sources of nutrition have received disproportionately less attention than prey when one considers how important non-prey foods are to the evolution and ecology of natural enemies. This book examines the intricate and diverse interactions between non-prey foods and natural enemies from both parties’ perspectives, beginning at an organismal level and taking the reader on a journey that illustrates how these interactions are inextricably tied to the outcome of biological control programs targeting insects and weed seeds.
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In a taxonomic study of yeasts recovered from nectar of flowers and associated insects in South Africa, eleven strains were found to represent two novel species. Morphological and physiological characteristics and sequence analyses of the D1/D2 large subunit rRNA gene, as well as the actin, RNA polymerase II, and elongation factor 2 genes showed that the two novel species belonged to the genus Metschnikowia. Metschnikowia drakensbergensis sp. nov. was recovered from nectar of Protea roupelliae and the beetle Heterochelus sp. This species belongs to the large-spored Metschnikowia clade and is closely related to M. proteae, with which mating reactions and single-spored asci were observed. Metschnikowia caudata sp. nov. was isolated from nectar of P. dracomontana, P. roupelliae, P. subvestita and a honey bee, and is a sister species to Candida hainanensis and M. lopburiensis. Analyses of the four genes demonstrated the existence of three separate phylotypes. Intraspecies matings lead to the production of mature asci of unprecedented morphology, with a long, flexuous tail. A single ascospore was produced in all compatible crosses, regardless of sequence phylotype. The two species appear to be endemic to South Africa. The ecology and habitat specificity of these novel species is discussed in terms of host plant and insect host species. The type cultures are: Metschnikowia drakensbergensis (type strain EBD-CdVSA09-2T=CBS 13649T=NRRL Y-63721T, MycoBank no. MB809688; allotype EBD-CdVSA10-2A=CBS13650A=NRRL Y-63720A); and Metschnikowia caudata (type strain EBD-CdVSA08-1T=CBS 13651T=NRRL Y-63722T, MycoBank no. MB809689; allotype EBD-CdVSA57-2A=CBS 13729A=NRRL Y-63723A).
Article
Sap-feeding insects harbor diverse microbial endosymbionts that play important roles in host ecology and evolution, including contributing to host pest status. The vine mealybug, Planococcus ficus, is a serious pest of grapevines, vectoring a number of pathogenic grape viruses. Previous studies have shown that virus transmission is abolished when mealybugs are raised in the laboratory on potato. To examine the possible role of microbial symbionts in virus transmission, the archaeal, bacterial, and fungal microbiota of field and laboratory P. ficus were characterized using molecular and classical microbiological methods. Lab and field colonies of P. ficus harbored different microbiota. While both were dominated by the bacterial obligate nutritional symbionts Moranella and Tremblaya, field samples also harbored a third bacterium that was allied with cluster L, a lineage of bacterial symbionts previously identified in aphids. Archaea were not found in any of the samples. Fungal communities in field-collected mealybugs were dominated by Metschnikowia and Cladosporium species, while those from laboratory-reared mealybugs were dominated by Alternaria and Cladosporium species. In conclusion, this study has identified a diverse set of microbes, most of which appear to be facultatively associated with P. ficus, depending on environmental conditions. The role of various members of the mealybug microbiome, as well as how the host plant affects microbial community structure, remains to be determined.
Article
Five strains representing two novel anamorphic yeast species were isolated from the external surface of sugarcane leaves (DMKU-RK16, DMKU-RK24, DMKU-RK198 and DMKU-RK500(T)) and rice leaf (DMKU-RK277(T)) by an enrichment technique. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, the sequence analysis of the D1/D2 domain of the large subunit (LSU) rRNA gene and the internal transcribed spacer region, the five strains were assigned to be two novel species of the Metschnikowia, although the formation of ascospores was not observed. Four strains (DMKU-RK16, DMKU-RK24, DMKU-RK198 and DMKU-RK500(T)) where the sequences of the D1/D2 domain of the LSU rRNA gene were identical and differed by 4.1 % nucleotide substitutions (20 nucleotide substitutions and four gaps out of 490 nt) from the type strain of Candida succicola, their closest known species in terms of pairwise sequence similarity, represent a single novel species, for which the name Metschnikowia saccharicola sp. nov. is proposed. The type strain is DMKU-RK500(T) (= BCC 50735(T) = NBRC 108904(T) = CBS 12575(T)). Strain DMKU-RK277(T) was closest to Candida hainanensis but with 4.0 % nucleotide substitutions (18 nucleotide substitutions and three gaps out of 449 nt) in the D1/D2 domain of the LSU rRNA gene was assigned to be Metschnikowia lopburiensis sp. nov. (type strain DMKU-RK277(T) = BCC 50731(T) = NBRC 108902(T) = CBS 12574(T)).
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We describe two related species of Metschnikowia isolated from Conotelus spp. (Coleoptera: Nitidulidae) of Costa Rican Convolvulacae. Metschnikowia similis sp. nov. is a sister species to Metschnikowia dekortorum (Lachance & Bowles 2002). These two species are distinguishable only by the ability to grow in the presence of 5 % NaCl, the sterility of hybrid asci, and rDNA sequencing. Metschnikowia colocasiae sp. nov. is a sister species to Metschnikowia arizonensis and can be differentiated from other species by a combination of the utilization of D-gluconate and L-lysine, growth at 34°C, and by the lack of ascospore formation in hybrids. The two new species occur in nature as haploid mating types and form acicular ascospores that reach 50 to 100 μm in length.
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Two new yeast species were isolated from flowers of Hibiscus species in Eastern and Northern Australia. Kodamaea kakaduensis is heterothallic, haploid, and similar to other Kodamaea species and to Candida restingae. Buds are often produced on short protuberances, and a true mycelium is formed. The new species differs from others by the assimilation of trehalose, melezitose, and xylitol, and is reproductively isolated. The cells of Candida tolerans are small and a pseudomycelium is formed. The carbon and nitrogen assimilation pattern is reminiscent of that of Zygosaccharomyces rouxii but the two are not closely related. Sequences of the D1/D2 domain of large subunit ribosomal DNA confirm the membership of K. kakaduensis in the genus Kodamaea and indicate that C. tolerans belongs to the Clavispora-Metschnikowia clade, with a moderate relatedness to Candida mogii. The type strains are: K. kakaduensis, UWO(PS)98-119.2 (h+, holotype, CBS 8611) and UWO(PS)98-117.1 (h-, isotype, CBS 8612); and C. tolerans, UWO(PS)98-115.5 (CBS 8613).Key words: Kodamaea, Candida, new yeast species, ribosomal DNA, whole-cell PCR.
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Insect associations with fungi are common and may be casual or highly specific and obligate. For example, more than 40 fungal species are as-sociated with the coffee berry borer (Hypothenemus hampei, Coleoptera: Cur-culionidae; Pérez et al. 2003) and about the same number with the subterranean termite Reticulitermes flavipes (Zoberi and Grace 1990; table 9.1). In one system 28 species of yeasts were isolated from the external parts of Drosophila serido and 18 species, including some not found on the external surfaces, from their crop (Morais et al. 1994; table 9.1). In relatively few cases a specific role for the fungus has been identified, as is the case for associations with ants (chapter 7), termites (chapter 8), and bark beetles (Chapter 11; Six 2003). These associations imply that different species are living together, reinforced by specific interactions, a concept popularized as symbiosis by de Bary (1879). Symbiotic associations have been classified as ectosymbiotic when the symbiont occurs outside the body of the host or endosymbiotic when the symbiont occurs internally, either intra-or extracellularly (Steinhaus 1949; Nardon and Nardon 1998; Margulis and Chapman 1998). Several interesting symbiotic associations occur between insects and yeasts. In all cases that are well studied, the benefit that accrues for the insect is better understood than the benefit to the yeasts. The term "yeast" is used to describe a particular fungal growth form (Steinhaus 1947; Alexopoulos et al. 1996). These predominantly unicellular ascomycetes di-vide by budding at some point in their life cycle (e.g., Saccharomyces). A sur-prising number of yeasts, however, also produce filamentous hyphae. At present, almost 700 species in 93 genera (Barnett et al. 2000) have been described in the ascomycete class Saccharomycetes, a group known informally as "true yeasts." True yeasts lack specialized sex organs, and sexual spores (ascospores) are produced in 211 Table 9.1. Yeasts internally isolated from insects. Insect Species Order: Family Yeast Location (Species) a Reference Stegobium paniceum Coleoptera: Anobiidae Mycetomes Escherich 1900 (= Sitodrepa panicea) (Saccharomyces) b Buchner 1930 Cecae (Torulopsis buchnerii) Gräbner 1954 Mycetome between foregut and midgut Pant and Fraenkel 1954 Mycetomes (Symbiotaphrina buchnerii) Kühlwein and Jurzitza 1961 Mycetomes and digestive tube (Torulopsis buchnerii) Bismanis 1976 Gut cecae (Symbiotaphrina buchnerii) Noda and Kodama 1996 Lasioderma serricorne Coleoptera: Anobiidae Mycetome between foregut and midgut van der Walt 1961; Jurzitza 1964 (Symbiotaphrina kochii) Gams and von Arx 1980 Noda and Kodama 1996
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Several strains of three new taxa of haploid heterothallic yeasts have been isolated from Various ephemeral flowers and associated insects in North and South America and Australia. Metschnikowia continentalis comprises two varieties and is a close relative of Metschnikowia hawaiiensis. Like the latter, it produces giant ascospores and lives in association with the insects that colonize flowers of the family Convolvulaceae. These species exhibit an unusual asymmetrical mating, but their rare asci are sterile. The varieties of M. continentalis undergo unlimited mating, but ascospores are rarely formed. Metschnikowia continentalis var. continentalis was isolated in central Brazil and is thought to occur across South America. Metschnikowia continentalis var. borealis was recovered in the Great Lakes area and may represent a North American population. Metschnikowia hibisci was found in the flowers and insects of various Hibiscus species in the Australian states of New South Wales and Queensland but appeared to be absent in members of the Convolvulaceae growing in the same areas. The latter forms intermediate-sized ascospores and one of its mating types forms conjugation tubes in the presence of cells of other Metschnikowia species. The three taxa share with M. hawaiiensis a large deletion in the D2 region of their large ribosomal DNA subunit, but in M. hibisci, the variable domain of the D2 region shares little, if any, sequence similarity with others. The type cultures are as follows: M. continentalis var, continentalis strains UFMG96-173 (h(+), CBS8429) and UFMG96-179 (h(-), CBS8430); M. continentalis var. borealis strains UWO(PS)96-104.2 (h(+), CBS 8431) and UWO(PS)96-101.1 (h(-), CBS8432); and M: hibisci strains UWO(PS)95-797.2 (h(+), CBS8433) and UWO(PS)95-805.1 (h(-), CBS8434).
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We studied specific yeast communities vectored by beetles, drosophilids, and bees that visit ephemeral flowers, mostly in the genus Hibiscus and in the families Convolvulaceae and Cactaceae, in the Neotropical, Nearctic, and Australian biogeographic regions. The communities consist mostly of yeasts in four clades centered around the genera Metschnikowia, Kodamaea, Wickerhamiella, and Starmerella. The largest geographic discontinuity occurs as a function of the nitidulid beetle species that dominate the non-pollinator insect visitors of the flowers. This partitions the New World, where the dominant beetle is in the genus Conotelus, from the Australian biogeographic region, dominated by species of Aethina. Distinct but sympatric insects may also carry radically different yeast communities.
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CLUSTAL X is a new windows interface for the widely-used progressive multiple sequence alignment program CLUSTAL W. The new system is easy to use, providing an integrated system for performing multiple sequence and profile alignments and analysing the results. CLUSTAL X displays the sequence alignment in a window on the screen. A versatile sequence colouring scheme allows the user to highlight conserved features in the alignment. Pull-down menus provide all the options required for traditional multiple sequence and profile alignment. New features include: the ability to cut-and-paste sequences to change the order of the alignment, selection of a subset of the sequences to be realigned, and selection of a sub-range of the alignment to be realigned and inserted back into the original alignment. Alignment quality analysis can be performed and low-scoring segments or exceptional residues can be highlighted. Quality analysis and realignment of selected residue ranges provide the user with a powerful tool to improve and refine difficult alignments and to trap errors in input sequences. CLUSTAL X has been compiled on SUN Solaris, IRIX5.3 on Silicon Graphics, Digital UNIX on DECstations, Microsoft Windows (32 bit) for PCs, Linux ELF for x86 PCs, and Macintosh PowerMac.
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Numerous strains of an unusual asexual yeast species were isolated from flowers of morning glory (Ipomoea spp., Convolvulaceae) and associated drosophilids and sap beetles of the genus Conotelus sampled in Hawaii and in Brazil. The nutritional profile of this yeast is similar to those of Metschnikowia hawaiiensis and Metschnikowia continentalis, which share the same habitats. The cells are large, hydrophobic, and tend to remain attached after budding, causing the colonies on agar media to have a convoluted appearance, reminiscent of popcorn. The sequences of the D1/D2 domain of large subunit rDNAs of strains from three different localities confirmed that a single species is involved, and that it is related to large-spored Metschnikowia species. The type strain is UWO(PS)91-672.1 (CBS 8466).
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Two new yeast species were isolated from flowers of Hibiscus species in Eastern and Northern Australia. Kodamaea kakaduensis is heterothallic, haploid, and similar to other Kodamaea species and to Candida restingae. Buds are often produced on short protuberances, and a true mycelium is formed. The new species differs from others by the assimilation of trehalose, melezitose, and xylitol, and is reproductively isolated. The cells of Candida tolerans are small and a pseudomycelium is formed. The carbon and nitrogen assimilation pattern is reminiscent of that of Zygosaccharomyces rouxii but the two are not closely related. Sequences of the D1/D2 domain of large subunit ribosomal DNA confirm the membership of K. kakaduensis in the genus Kodamaea and indicate that C. tolerans belongs to the Clavispora-Metschnikowia clade, with a moderate relatedness to Candida mogii. The type strains are: K. kakaduensis, UWO(PS)98-119.2 (h+, holotype, CBS 8611) and UWO(PS)98-117.1 (h-, isotype, CBS 8612); and C. tolerans, UWO(PS)98-115.5 (CBS 8613).
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Two new haplontic heterothallic species of Metschnikowia were isolated from floricolous insects and flowers. Metschnikowia lochheadii was recovered from insects found in various flowers on the Hawaiian Islands of Kauai and Maui, and from Conotelus sp. (Coleoptera: Nitidulidae) in northwestern Guanacaste Province, Costa Rica. The morphology, physiology, and sexual cycle are typical of the large-spored Metschnikowia species, and the partial ribosomal DNA large subunit (D1D2) sequences suggest that the new species is most closely related to Candida ipomoeae. Metschnikowia lochheadii is nearly indistinguishable from its ascogenous relatives and conjugates freely with Metschnikowia continentalis, forming sterile asci. It also exhibits asymmetric mating with Metschnikowia hawaiiensis. Metschnikowia drosophilae was found in morning glory (Ipomoea sp.) flowers and associated Drosophila bromeliae on Grand Cayman Island. Its nutritional profile is atypical of the genus, being the only species that does not utilize sucrose or maltose as carbon sources, and one of the few that does not utilize melezitose. D1D2 sequences show that Metschnikowia drosophilae is a sister species to Candida torresii, to which it bears considerable similarity in nutritional profile. The type cultures are: Metschnikowia lochheadii, strains UWO(PS)00-133.2 = CBS 8807 (h+, holotype) UWO(PS)99-661.1 = CBS 8808 (h-, isotype); and Metschnikowia drosophilae, strains UWO(PS)83-1135.3 = CBS 8809 (h+, holotype) and UWO(PS)83-1143.1 = CBS 8810 (h-, isotype).
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The phenotypic and genetic heterogeneity of the basidiomycetous yeast species Rhodosporidium kratochvilovae was investigated in a group of recent isolates and collection strains. A polyphasic taxonomic approach was followed which included micromorphological studies, nuclear staining, determination of sexual compatibility, physiological characterization, comparison of electrophoretic isoenzyme patterns, PCR fingerprinting, determination of mol% G+C, DNA-DNA reassociation experiments and 26S and ITS rDNA sequence analysis. The results allowed a more natural circumscription of the species, both from the genetic and phenotypic perspectives. The relationships with anamorphic species of the genus Rhodotorula were studied and isolates previously identified as Rhodotorula glutinis were found to belong to Rhodosporidium kratochvilovae. Other isolates included in the study were found to represent members of Rhodotorula glutinis var. dairenensis. Rhodosporidium kratochvilovae was found to include heterothallic strains, besides those already known to be self-sporulating. A total of 17 isolates, which were found to belong to this species, were heterothallic, self-sporulating and anamorphic strains. It is anticipated that integrated polyphasic studies of basidiomycetous yeasts will provide a more coherent classification system and the basis for accurate identification schemes, which in turn are essential for detailed ecological studies.
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A novel asexual ascomycetous yeast, Candida kunwiensis (SG99-26T = KCTC 17041T = CBS 9067T), was isolated from sweet potato (Ipomoea batatas) flowers in Korea and from the body surface of pollinating bumblebees in Germany. Comparative analysis of the D1/D2 domain of 26S rDNA of all available sequences for ascomycetous yeasts showed that the novel species was phylogenetically related to the genus Metschnikowia, but the sequence similarity was low. Morphologically and physiologically, C. kunwiensis in many ways resembles Metschnikowia pulcherrima, but can be distinguished from this species by its ability to assimilate lactic acid and its inability to produce pulcherrimin.
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One of the most pervasive challenges in molecular phylogenetics is the incongruence between phylogenies obtained using different data sets, such as individual genes. To systematically investigate the degree of incongruence, and potential methods for resolving it, we screened the genome sequences of eight yeast species and selected 106 widely distributed orthologous genes for phylogenetic analyses, singly and by concatenation. Our results suggest that data sets consisting of single or a small number of concatenated genes have a significant probability of supporting conflicting topologies. By contrast, analyses of the entire data set of concatenated genes yielded a single, fully resolved species tree with maximum support. Comparable results were obtained with a concatenation of a minimum of 20 genes; substantially more genes than commonly used but a small fraction of any genome. These results have important implications for resolving branches of the tree of life.
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Fourteen yeast isolates comprising three taxa were cultured from digestive tracts of adult Chrysoperla species (Neuroptera: Chrysopidae) and their eggs. The yeast taxa were distinguished based on an estimated molecular phylogeny, DNA sequences and traditional taxonomic criteria. The new yeasts are closely related to Metschnikowia pulcherrima but are sufficiently distinguished by sequence comparison of rRNA gene sequences to consider them as novel species. Here, three novel species are described and their relationships with other taxa in the Saccharomycetes are discussed. Metschnikowia chrysoperlae sp. nov. (type strain, NRRL Y-27615T = CBS 9803T) produced needle-shaped ascospores and was the only teleomorph found. Large numbers of chlamydospores similar to those observed in M. pulcherrima were also produced. The other two novel species are asexual yeasts, Candida picachoensis sp. nov. (type strain, NRRL Y-27607T = CBS 9804T) and Candida pimensis sp. nov. (type strain, NRRL Y-27619T = CBS 9805T), sister taxa of M. chrysoperlae and M. pulcherrima. A specialized relationship between yeasts and lacewing hosts may exist, because the yeasts were isolated consistently from lacewings only. Although M. chrysoperlae was isolated from eggs and adult lacewings, suggesting the possibility of vertical transmission, no yeast was isolated from larvae.
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A major clade of new yeast taxa from the digestive tract of basidiocarp-feeding beetles is recognized based on rRNA gene sequence analyses. Almost 30 % of 650 gut isolates formed a statistically well-supported clade that included Candida tanzawaensis. The yeasts in the clade were isolated from 11 families of beetles, of which Tenebrionidae and Erotylidae were most commonly sampled. Repeated isolation of certain yeasts from the same beetle species at different times and places indicated strong host associations. Sexual reproduction was never observed in the yeasts. Based on comparisons of small- and large-subunit rRNA gene sequences and morphological and physiological traits, the yeasts were placed in Candida ambrosiae and in 16 other undescribed taxa. In this report, the novel species in the genus Candida are described and their relationships with other taxa in the Saccharomycetes are discussed. The novel species and their type strains are as follows: Candida guaymorum (NRRL Y-27568(T)=CBS 9823(T)), Candida bokatorum (NRRL Y-27571(T)=CBS 9824(T)), Candida kunorum (NRRL Y-27580(T)=CBS 9825(T)), Candida terraborum (NRRL Y-27573(T)=CBS 9826(T)), Candida emberorum (NRRL Y-27606(T)=CBS 9827(T)), Candida wounanorum (NRRL Y-27574(T)=CBS 9828(T)), Candida yuchorum (NRRL Y-27569(T)=CBS 9829(T)), Candida chickasaworum (NRRL Y-27566(T)=CBS 9830(T)), Candida choctaworum (NRRL Y-27584(T)=CBS 9831(T)), Candida bolitotheri (NRRL Y-27587(T)=CBS 9832(T)), Candida atakaporum (NRRL Y-27570(T)=CBS 9833(T)), Candida panamericana (NRRL Y-27567(T)=CBS 9834(T)), Candida bribrorum (NRRL Y-27572(T)=CBS 9835(T)), Candida maxii (NRRL Y-27588(T)=CBS 9836(T)), Candida anneliseae (NRRL Y-27563(T)=CBS 9837(T)) and Candida taliae (NRRL Y-27589(T)=CBS 9838(T)).
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Three heterothallic, haplontic yeast species, Metschnikowia hamakuensis, Metschnikowia kamakouana and Metschnikowia mauinuiana, are described from isolates associated with endemic nitidulid beetles living on various endemic plants on three Hawaiian islands. As morphospecies, they are similar to Metschnikowia hawaiiensis, but based on mating compatibility and ascospore formation, they can be assigned clearly to distinct biological species. Analysis of ITS/5.8S and D1/D2 large subunit rDNA sequences shows that, with M. hawaiiensis and two other isolates, these species form a distinct subclade within the large-spored Metschnikowia species, indicating that they are Hawaiian endemics. Type cultures are: M. hamakuensis, UWOPS 04-207.1(T) = CBS 10056(T) = NRRL Y-27834(T) (type, h(+)) and UWOPS 04-204.1 = CBS 10055 = NRRL Y-27833 (allotype, h(-)); M. kamakouana, UWOPS 04-112.5(T) = CBS 10058(T) = NRRL Y-27836(T) (type, h(+)) and UWOPS 04-109.1 = CBS 10057 = NRRL Y-27835 (allotype, h(-)); and M. mauinuiana, UWOPS 04-190.1(T) = CBS 10060(T) = NRRL Y-27838(T) (type, h(+)) and UWOPS 04-110.4 = CBS 10059 = NRRL Y-27837 (allotype, h(-)).
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Two new species of the ascosporic yeast genus Metschnikowia were isolated from nectaries and associated muscoid flies of flowers from the common milkweed (Asclepias syriaca) in North America, and are described as Metschnikowia vanudenii [type strain=PYCC 4650(T)=CBS 9134(T)=NRRL Y-27243(T)=UWO(PS) 86A4.1(T)] and Metschnikowia lachancei [type strain=PYCC 4605(T)=CBS 9131(T)=NRRL Y-27242(T)=UWO(PS) 7ASB2.3(T)]. As with the previously described Metschnikowia gruessii, M. vanudenii has vegetative cells with an 'aeroplane' or cross-like configuration, produces ovoid chlamydospores and forms ellipsoidopedunculate asci with two acicular ascospores. Metschnikowia lachancei is distinguished from other Metschnikowia species by formation of club-shaped asci with 1-2 thick clavate ascospores. The phylogenetic positions of the proposed new species within Metschnikowia were determined from sequence analysis of the D1/D2 domain of 26S rDNA. The new species show low nuclear DNA relatedness with neighbouring taxa.
Chapter
This chapter focuses on Metschnikowia and its member species. The cells of this genus are spheroidal to ellipsoidal, as well as pyriform, cylindroid, or lunate. Vegetative reproduction in this genus occurs through multilateral budding. Its asci are elongate and its ascospores are needle-shaped, attenuate at one or both ends, and without a whip-like appendage. Some species are parasitic in invertebrates, as well as free-living in aquatic habitats, while others are terrestrial, free-living, and often associated with flowers. The sugars are fermented by most species and nitrate is not assimilated. The member species of this genus include Metschnikowia agaves; Metschnikowia australis; Metschnikowia bicuspidata including its three variants Metschnikowia bicuspidata, Metschnikowia bicuspidata var. californica, and Metschnikowia bicuspidata var. chathamia; Metschnikowia gruessii; Metschnikowia hawaiiensis; Metschnikowia krissii; and Metschnikowia lunata. The Metschnikowia agaves species, after one day on yeast carbon base agar (without added nitrogen source) and mixed strains of complementary mating types, give rise to long (several cell lengths) conjugation tubes, or elongated cells. After 3 days at 25° C, mature asci are observed that are pleomorphic in shape but are usually quasi-cylindrical and conjugated. In the case of Metschnikowia australis, a large clavate ascus develops containing two acicular spores after the conjugation of two haploid cells of complementary mating types.
Article
We have regularly cultured yeasts from the gut of certain beetles in our ongoing research. In this study cloned PCR products amplified from the gut contents of certain mushroom-feeding and wood-ingesting beetles in four families (Erotylidae, Tenebrionidae, Ciidae, and Passalidae) were sequenced and compared with culture results. Cultural techniques detected some yeasts present in the gut of the beetles, including a Pichia stipitis-like yeast associated with wood-ingesting passalid beetles. Clone sequences similar to several ascomycete yeasts and Malassezia restricta, a fastidious basidiomycetous yeast requiring special growth media, however, were not detected by culturing. Unexpectedly, phylogenetic analysis of additional clone sequences discovered from passalid beetles showed similarity to members of the Parabasalia, protists known from other wood-ingesting insects, termites, and wood roaches. Examination of all gut regions of living passalids, however, failed to reveal parabasalids, and it is possible that they were parasites in the gut tissue present in low numbers.
Article
Two novel representatives of the yeast genus Candida, isolated from advanced stages of degradation from fallen trunks of Nothofagus dombeyii (Mirb.) Blume and Laurelia sempervirens Weim., in the evergreen rainy Valdivian forest of southern Chile, are described and illustrated. The strains differ from all accepted Candida species to warrant their establishment as two new species: Candida petrohuensis and Candida rancensis.
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Publisher Summary This chapter focuses on the methods used for the isolation, maintenance, and identification of yeasts. Yeasts have been recovered from widely differing aquatic and terrestrial sources, as well as from the atmosphere. Many types of yeast occur widely, whereas some appear to be confined to restricted habitats. Yeasts seldom occur in the absence of either molds or bacteria. Consequently, selective techniques are often used for recovery of yeasts, employing media which permit the yeast to grow while suppressing molds and bacteria. The composition of such media is determined by the fact that yeasts are, as a rule, capable of developing at pH levels and water activities, which reduce or inhibit the growth of bacteria. Antibiotics may also be used to suppress bacteria. When yeasts are present in low numbers, their isolation may require enrichment using media and conditions which favor the growth of yeasts over other microorganisms. Yeast cultures are best maintained on a medium which contains glucose as the only source of carbon as this reduces the risk of changes in growth and fermentative patterns due to the selection of mutants. Many basidiomycetous yeasts do not survive well during prolonged storage on a glucose-peptone medium, although they grow well on it. Potato-dextrose agar is used when cultures of such yeasts are to be kept for a long time. The majority of yeasts may be stored at temperatures between 4 and 12° C and subcultured at intervals of 6 to 8 months. Yeasts such as Arxiozyma and Malassezia, may have to be subcultured every month.
Article
The indigenous gut microflora associated with the alimentary canal of 24 field-collected Chrysoperla rufilabris adults was examined qualitatively and quantitatively at five sample times and two locations in Mississippi. Yeasts were isolated from the diverticula of 17 insects, and there was no effect of location or sample time on the occurrence of yeasts. Metschnikowia pulcherrima was present in all of the diverticula that contained yeasts, and densities in this gut region ranged from 5.3 × 102 to 5.4 × 105 colony forming units (CFUs). Numerous yeast cells were observed in diverticula, and these cells accumulated within pronounced diverticular folds. Large numbers of Met. pulcherrima were also observed in the foregut, and to a lesser extent in the midgut and hindgut of field-collected adults. In an ancillary experiment, no yeasts were observed in Cry. rufilabris adults that had recently eclosed (ca. 24 h) in the laboratory. Thirteen of the insects were positive for filamentous fungi, but the majority of the gut regions contained <102 CFUs. Furthermore, there was very little commonality in the taxa isolated among the sample times and locations suggesting that filamentous fungi are transients in Cry. rufilabris alimentary canals. Nineteen insects were positive for bacteria. Populations varied among the gut regions, and more bacteria were recovered from the midguts of adults at one collection site. Twenty-five aerobic bacterial taxa were isolated, and Enterobacter aerogenes was the most commonly isolated taxon. However, this bacterium was only isolated from four insects on four occasions. Other bacterial taxa were even less frequently isolated, suggesting that bacteria are likely transients. Our findings indicate that Cry. rufilabris adults may form a symbiosis with the yeast, Met. pulcherrima, but not with filamentous fungi or bacteria. This information will facilitate studies to elucidate the mechanism and impact of this interaction, and may facilitate the rearing of this important predator for use in biological control programs against pest insects.
Article
The ability of symbiotic yeast found in larvae and adults of Lasioderma serricorne (F.) to detoxify xenobiotics hydrolytically in situ was investigated. The symbionts of larvae and adults hydrolyzed 1-naphthyl acetate, a reaction that was inhibited by DEF (S,S,S-tributyl phosphorotrithioate, Chem Service) and mercuric chloride. The yeasts also accumulated tannic acid, which was hydrolyzed to gallic acid. Thus, in addition to nutritional contributions that were previously demonstrated, these symbionts are capable of assisting the survival of the host by detoxifying xenobiotics.
Article
ABSTRACT To investigate host specialization in Macrophomina phaseolina, the fungus was isolated from soybean, corn, sorghum, and cotton root tissue and soil from fields cropped continuously to these species for 15 years in St. Joseph, LA. Chlorate phenotype of each isolate was determined after growing on a minimal medium containing 120 mM potassium chlorate. Consistent differences in chlorate sensitivity were detected among isolates from different hosts and from soil versus root. To further explore genetic differentiation among fungal isolates from each host, these isolates were examined by restriction fragment length polymorphism and random amplified polymorphic DNA (RAPD) analysis. No variations were observed among isolates in restriction patterns of DNA fragments amplified by polymerase chain reaction covering the internal transcribed spacer region, 5.8S rRNA and part of 25S rRNA, suggesting that M. phaseolina constitutes a single species. Ten random primers were used to amplify the total DNA of 45 isolates, and banding patterns resulting from RAPD analysis were compared with the neighbor-joining method. Isolates from a given host were genetically similar to each other but distinctly different from those from other hosts. Chlorate-sensitive isolates were distinct from chlorate-resistant isolates within a given host. In greenhouse tests, soybean, sorghum, corn, and cotton were grown separately in soil infested with individual isolates of M. phaseolina that were chosen based on their host of origin and chlorate phenotype. Root colonization and plant weight were measured after harvesting. More colonization of corn roots occurred when corn was grown in soil containing corn isolates compared with isolates from other hosts. However, there was no host specialization in isolates from soybean, sorghum, or cotton. More root colonization in soybean occurred with chlorate-sensitive than with chlorate-resistant isolates.
Article
'BLAST 2 Sequences', a new BLAST-based tool for aligning two protein or nucleotide sequences, is described. While the standard BLAST program is widely used to search for homologous sequences in nucleotide and protein databases, one often needs to compare only two sequences that are already known to be homologous, coming from related species or, e.g. different isolates of the same virus. In such cases searching the entire database would be unnecessarily time-consuming. 'BLAST 2 Sequences' utilizes the BLAST algorithm for pairwise DNA-DNA or protein-protein sequence comparison. A World Wide Web version of the program can be used interactively at the NCBI WWW site (http://www.ncbi.nlm.nih.gov/gorf/bl2.++ +html). The resulting alignments are presented in both graphical and text form. The variants of the program for PC (Windows), Mac and several UNIX-based platforms can be downloaded from the NCBI FTP site (ftp://ncbi.nlm.nih.gov).
Article
We studied specific yeast communities vectored by beetles, drosophilids, and bees that visit ephemeral flowers, mostly in the genus Hibiscus and in the families Convolvulaceae and Cactaceae, in the Neotropical, Nearctic, and Australian biogeographic regions. The communities consist mostly of yeasts in four clades centered around the genera Metschnikowia, Kodamaea, Wickerhamiella, and Starmerella. The largest geographic discontinuity occurs as a function of the nitidulid beetle species that dominate the non-pollinator insect visitors of the flowers. This partitions the New World, where the dominant beetle is in the genus Conotelus, from the Australian biogeographic region, dominated by species of Aethina. Distinct but sympatric insects may also carry radically different yeast communities.
Article
Two new haplontic heterothallic species of Metschnikowia were discovered in flowers and associated beetles. Metschnikowia arizonensis was recovered from flowers of cholla cactus (Opuntia echinocarpa) and a specimen of Carpophilus sp. (Coleoptera: Nitidulidae) found in these flowers, in Arizona. Metschnikowia dekortorum was isolated in specimens of the nitidulid beetle Conotelus sp. captured in flowers of two species of Ipomoea in northwestern Guanacaste Province, Costa Rica. The sexual cycle of these yeasts is typical of the large-spored Metschnikowia species, but the asci and spores are intermediate in size between these and other members of the genus. The physiology is consistent with that of most Metschnikowia species except that both species fail to utilize lysine as sole nitrogen source. Also, M. arizonensis utilizes fewer carbon compounds than most species and exhibits considerable variability among strains at this level. Partial ribosomal DNA large-subunit (D1/D2) sequences suggest that M. arizonensis and M. dekortorum are moderately related sister species whose positions are intermediate between the large-spored species Metschnikowia and Metschnikowia hibisci. The type cultures are: M. arizonensis, strains UWO(PS)99-103.3.1=CBS 9064=NRRL Y-27427 (h(+), holotype) and UWO(PS)99-103.4=CBS 9065=NRRL Y-27428 (h(-), isotype); and M. dekortorum, strains UWO(PS)01-142b3=CBS 9063=NRRL Y-27429 (h(+), holotype) and UWO(PS)01-138a3=CBS 9062=NRRL Y-27430 (h(-), isotype).
Article
A new haplontic heterothallic species of Metschnikowia and two related asexual yeast species were discovered in morning glory flowers and associated insects. Metschnikowia santaceciliae came from Conotelus (Coleoptera: Nitidulidae) and other insect species associated with flowers of Ipomoea indica (purple morph) in Costa Rica. Candida hawaiiana and Candida kipukae were found in I. indica (syn. I. acuminata) and its insects in Hawai'i, and the former was also isolated in a specimen of Conotelus collected on Merremia tuberosa (Convolvulaceae) in Costa Rica. The three species have nearly identical physiological profiles, typical of the genus Metschnikowia. The sequences of the D1/D2 domains of their large subunit ribosomal DNA confirm that the species belong to the Metschnikowia clade, even though they share a very low degree of inter-relatedness. M. santaceciliae is a sister species to Metschnikowia continentalis. C. kipukae is a basal member of the large-spored Metschnikowia subclade, and C. hawaiiana has a weak affinity to Metschnikowia agaves. Two of the three species appear to be endemic. The type cultures are: Metschnikowia santaceciliae, strains UWO(PS)01-517a1=CBS 9148=NRRL Y-27475 (h(+, holotype) and UWO(PS)01-520a1=CBS 9149=NRRL Y-27476 (h-, isotype); Candida hawaiiana, strain UWO(PS)91-698.3=CBS 9146=NRRL Y-27473; Candida kipukae, strain UWO(PS)00-669.2=CBS 9147=NRRL Y-27474.
Article
During a survey of insect gut micro-organisms, we consistently isolated Pichia stipitis-like yeasts (Fungi: Ascomycota, Saccharomycetes) from the wood-ingesting beetles, Odontotaenius disjunctus and Verres sternbergianus (Coleoptera: Passalidae). The yeasts were isolated from passalid beetles over a wide area, including the eastern and midwestern USA and Panama. Phylogenetic analyses of the nuclear encoded small and large subunit rRNA gene (rDNA) sequences distinguished a well-supported clade consisting of the passalid yeasts and Pichia stipitis, P. segobiensis, Candida shehatae and C. ergatensis. Members of this clade have the ability to ferment and assimilate xylose or to hydrolyse xylan, major components of the polysaccharide, hemicellulose. Sexual reproduction was present in the passalid isolates but was rare among the gut yeasts of other beetles to which they were compared. Minor genetic and phenotypic variation among some of the passalid yeasts was detected using markers from the internal transcribed spacer region of the rDNA repeat unit, morphology, and in vitro metabolic tests. The consistent association of xylose-fermenting yeasts of almost identical genotypes with passalid beetles across a broad geographical distribution, suggests a significant symbiotic association.
Article
We have regularly cultured yeasts from the gut of certain beetles in our ongoing research. In this study cloned PCR products amplified from the gut contents of certain mushroom-feeding and wood-ingesting beetles in four families (Erotylidae, Tenebrionidae, Ciidae, and Passalidae) were sequenced and compared with culture results. Cultural techniques detected some yeasts present in the gut of the beetles, including a Pichia stipitis-like yeast associated with wood-ingesting passalid beetles. Clone sequences similar to several ascomycete yeasts and Malassezia restricta, a fastidious basidiomycetous yeast requiring special growth media, however, were not detected by culturing. Unexpectedly, phylogenetic analysis of additional clone sequences discovered from passalid beetles showed similarity to members of the Parabasalia, protists known from other wood-ingesting insects, termites, and wood roaches. Examination of all gut regions of living passalids, however, failed to reveal parabasalids, and it is possible that they were parasites in the gut tissue present in low numbers.
Article
New yeasts in the Pichia guilliermondii clade were isolated from the digestive tract of basidiocarp-feeding members of seven families of Coleoptera. A molecular phylogeny and unique traits placed eight isolates in Candida fermentati and three undescribed taxa in the genus Candida. The new species and type strains are C. smithsonii (type strain NRRL Y-27642T), C. athensensis (type strain NRRL Y-27644T), and C. elateridarum (type strain NRRL Y-27647T). Based on comparison of small-and large-subunit rDNA sequences, C. smithsonii and C. athensensis form a statistically well-supported subclade with P. guilliermondii, C. xestobii, and C. fermentati; C. elateridarum is basal to this subclade.
Article
Two yeast strains, producing needle-shaped ascospores under suitable conditions, were isolated from grapes grown in Hungary. Based on these two strains, Metschnikowia viticola (type strain NCAIM Y.01705, CBS 9950, JCM 12561) is proposed as a new yeast species. Considering its phenotypic features, the restriction fragment patterns of 18S rDNA and the sequence of the D1/D2 domain of 26S rDNA, the proposed new species is closely related to Candida kofuensis.
Article
We isolated over 650 yeasts over a three year period from the gut of a variety of beetles and characterized them on the basis of LSU rDNA sequences and morphological and metabolic traits. Of these, at least 200 were undescribed taxa, a number equivalent to almost 30% of all currently recognized yeast species. A Bayesian analysis of species discovery rates predicts further sampling of previously sampled habitats could easily produce another 100 species. The sampled habitat is, thereby, estimated to contain well over half as many more species as are currently known worldwide. The beetle gut yeasts occur in 45 independent lineages scattered across the yeast phylogenetic tree, often in clusters. The distribution suggests that the some of the yeasts diversified by a process of horizontal transmission in the habitats and subsequent specialization in association with insect hosts. Evidence of specialization comes from consistent associations over time and broad geographical ranges of certain yeast and beetle species. The discovery of high yeast diversity in a previously unexplored habitat is a first step toward investigating the basis of the interactions and their impact in relation to ecology and evolution.
Article
14 different yeasts were isolated from the gut of a variety of insects, including beetles, lacewings, fishflies, craneflies, and a cockroach. One of the yeasts was found both in the gut and on the body surface of a beetle larva. Based on ribosomal DNA sequence comparisons and phenotypic characters, the yeasts were identified as Candida membranifaciens, C. tenuis, Pichia nakazawae, and nine undescribed taxa in Saccharomycotina. All the undescribed taxa reproduced only asexually, and they fit within the limits of the polyphyletic genus Candida. The new species and their type strains are Candida blattariae NRRL Y-27703T, C. amphixiae NRRL Y-27704T, C. michaelii NRRL Y-27705T, C. cerambycidarum NRRL Y-27706T, C. gorgasii NRRL Y-27707T, C. endomychidarum NRRL Y-27708T, C. temnochilae NRRL Y-27763T, C. sinolaborantium NRRL Y-27765T, and C. lessepsii NRRL Y-27766T spp. nov. Phylogenetic analysis of combined small and large subunit ribosomal DNA sequences placed C. amphixiae, C. michaelii, C. cerambycidarum, C. gorgasii, C. endomychidarum, and C. lessepsii in a statistically well supported clade with C. blattariae, C. membranifaciens, C. friedrichii, and C. buinensis as sisters to the clade. The other two new taxa, C. temnochilae and C. sinolaborantium, formed an independent clade basal to the major clade containing C. membranifaciens and closely related taxa. C. sinolaborantium occurred in both Panama and the USA, but there were genetic differences between the isolates from the two places.
Feeding of adult caddisflies Trichoptera Newsletter 16: 18. New yeast species from insects Martin M Invertebrate–Microbe Interactions Reidentification of yeast strains deposited as Candida agrestis, with a description of Candida kofuensis sp. nov
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The role of yeasts as insect endosymbi-onts Insect Fungal Associations: Ecology and Evolution
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Vega FE, Dowd PF, 2005. The role of yeasts as insect endosymbi-onts. In: Vega FE, Blackwell M (eds), Insect Fungal Associations: Ecology and Evolution. Oxford University Press, New York, pp. 211–243.
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The beetle gut as a habitat for new species of yeasts Insect Fungal Associations: Ecology and Evolution
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Suh S-O, Blackwell M, 2005. The beetle gut as a habitat for new species of yeasts. In: Vega FE, Blackwell M (eds), Insect Fungal Associations: Ecology and Evolution. Oxford University Press, New York, pp. 244–256.
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Rokas A, Williams BL, King N, Carroll SB, 2003. Genome-scale approaches to resolving incongruence in molecular phyloge-nies. Nature 425: 798–804.
Feeding of adult caddisflies
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Malicky H, 1989. Feeding of adult caddisflies. Trichoptera Newsletter 16: 18.
American Beetles, Volume II: Polyphaga: Scarabaeoidea through Curculionoidea
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Metschnikowia Kamiensky The Yeasts: a Taxonomic Study
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Yeasts: Characteristics and Identification
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Barnett JA, Payne RW, Yarrow D, 2000. Yeasts: Characteristics and Identification, 3rd edn. Cambridge University Press, Cambridge.
Symbiont-mediated detoxification in insect herbivores
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