Martin Meijer

CBS Fungal Biodiversity Centre - Royal Netherlands Academy of Arts and Sciences, Utrecht, Utrecht, Netherlands

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Publications (18)81.03 Total impact

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    ABSTRACT: Abstract Black Aspergilli (Aspergillus section Nigri) are widely distributed in various habitats. They act as food spoilage organisms, human pathogens, and mycotoxin producers and are frequently encountered in indoor environments. Black Aspergilli, specifically A. niger, A. welwitschiae, and A. carbonarius, produce different ochratoxins and fumonisins. Ochratoxins are known to induce renal disorders following inhalation, which necessitates the determination of potential mycotoxin-producing species in our environment. This paper aimed to compare the diversity and species distribution of black Aspergilli in the indoor environments of six different countries using morphological and molecular methods. A total of 178 black Aspergillus isolates were identified from six countries. In contrast with results from previous studies, A. niger was not the only black Aspergillus detected in indoor air. Species distribution differed among countries, although the distribution in European countries (Croatia, Hungary, the Netherlands, and Turkey) with a temperate climate was considerably similar. The highest species diversity was observed in indoor samples from Thailand, while the lowest was found in Algeria. Potentially ochratoxin- and fumonisin-producing fungi were detected in the indoor air of all six countries. Further studies need to clarify the effect of these fungi and their mycotoxins on human and animal health.
    Archives of Industrial Hygiene and Toxicology 04/2014; · 0.67 Impact Factor
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    ABSTRACT: Disseminated infections caused by members of the Fusarium fujikuroi species complex (FFSC) occur regularly in immunocompromised patients. Here, we present the first human case caused by FFSC-member Fusarium andiyazi. Fever, respiratory symptoms and abnormal computerised tomography findings developed in a 65-year-old man with acute myelogenous leukaemia who was under posaconazole prophylaxis during his remission-induction chemotherapy. During the course of infection, two consecutive blood galactomannan values were found to be positive, and two blood cultures yielded strains resembling Fusarium species, according to morphological appearance. The aetiological agent proved to be F. andiyazi based on multilocus sequence typing. The sequencing of the internal transcribed spacer region did not resolve the closely related members of the FFSC, but additional data on partial sequence of transcription elongation factor 1 alpha subunit did. A detailed morphological study confirmed the identification of F. andiyazi, which had previously only been reported as a plant pathogen affecting various food crops.
    Mycoses 04/2014; 57(4):249-55. · 1.28 Impact Factor
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    ABSTRACT: As part of a worldwide survey of the indoor mycobiota, dust was collected from nine countries. Analyses of dust samples included the culture-dependent dilution-to-extinction method and the culture-independent 454-pyrosequencing. Of the 7 904 isolates, 2 717 isolates were identified as belonging to Aspergillus, Penicillium and Talaromyces. The aim of this study was to identify isolates to species level and describe the new species found. Secondly, we wanted to create a reliable reference sequence database to be used for next-generation sequencing projects. Isolates represented 59 Aspergillus species, including eight undescribed species, 49 Penicillium species of which seven were undescribed and 18 Talaromyces species including three described here as new. In total, 568 ITS barcodes were generated, and 391 β-tubulin and 507 calmodulin sequences, which serve as alternative identification markers.
    Studies in Mycology 01/2014; · 6.23 Impact Factor
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    ABSTRACT: Aspergillus section Circumdati or the Aspergillus ochraceus group, includes species with rough walled stipes, biseriate conidial heads, yellow to ochre conidia and sclerotia that do not turn black. Several species are able to produce mycotoxins including ochratoxins, penicillic acids, and xanthomegnins. Some species also produce drug lead candidates such as the notoamides. A polyphasic approach was applied using morphological characters, extrolite data and partial calmodulin, β-tubulin and ITS sequences to examine the evolutionary relationships within this section. Based on this approach the section Circumdati is revised and 27 species are accepted, introducing seven new species: A. occultus, A. pallidofulvus, A. pulvericola, A. salwaensis, A. sesamicola, A. subramanianii and A. westlandensis. In addition we correctly apply the name A. fresenii (≡ A. sulphureus (nom. illeg.)). A guide for the identification of these 27 species is provided. These new species can be distinguished from others based on morphological characters, sequence data and extrolite profiles. The previously described A. onikii and A. petrakii were found to be conspecific with A. ochraceus, whilst A. flocculosus is tentatively synonymised with A. ochraceopetaliformis, despite extrolite differences between the two species. Based on the extrolite data, 13 species of section Circumdati produce large amounts of ochratoxin A: A. affinis, A. cretensis, A. fresenii, A. muricatus, A. occultus, A. ochraceopetaliformis (A. flocculosus), A. ochraceus, A. pseudoelegans, A. pulvericola, A. roseoglobulosus, A. sclerotiorum, A. steynii and A. westerdijkiae. Seven additional species produce ochratoxin A inconsistently and/or in trace amounts: A. melleus, A. ostianus, A. persii, A. salwaensis, A. sesamicola, A. subramanianii and A. westlandensis. The most important species regarding potential ochratoxin A contamination in agricultural products are A. ochraceus, A. steynii and A. westerdijkiae.
    Studies in Mycology 01/2014; · 6.23 Impact Factor
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    ABSTRACT: BACKGROUND: Aspergillus tubingensis is a black Aspergillus belonging to the Aspergillus section Nigri, which includes species that morphologically resemble Aspergillus niger. Recent developments in species determination have resulted in clinical isolates presumed to be Aspergillus niger being reclassified as Aspergillus tubingensis by sequencing. We present a report of a patient with an osteomyelitis of the maxillary bone with a probable invasive Aspergillus tubingensis infection. CASE PRESENTATION: We describe an immune compromised patient suffering from osteomyelitis of the maxillary bone after tooth extraction. The osteomyelitis probably resulted in dentogenic pansinusitis presenting as an acute ethmoiditis. Histologic examination of biopsy samples showed osteomyelitis, and inflammation of the surrounding connective tissue. Cultures of the alveolar wound grew Aspergillus tubingensis. The patient was treated with liposomal amphoterocin B, which was changed to oral treatment with voriconazole based on susceptibility testing (MIC for voriconazole was 1 mug/ml). CONCLUSION: This case shows that Aspergillus tubingensis may have the potential to cause severe invasive infections in immunocompromised hosts. A larger proportion of Aspergillus tubingensis isolates are less susceptible to azoles compared to Aspergillus niger. Therefore, correct species identification and susceptibility testing is crucial for the choice of anti-fungal treatment, screening of azole resistance, and characterization of the pathogenic potential of the various species within Aspergillus section Nigri.
    BMC Infectious Diseases 02/2013; 13(1):59. · 3.03 Impact Factor
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    ABSTRACT: Geosmithia argillacea in recent years has been increasingly reported in man and animal and can be considered as an emerging pathogen. The taxonomy of Geosmithia was recently studied and Geosmithia argillacea and related species were transferred to the new genus Rasamsonia. The diversity among a set of Rasamsonia argillacea strains including twenty-eight clinical strains was studied and antifungal susceptibility profiles were generated. Data obtained from morphological studies and from phylogenetic analyses of ITS and partial β-tubulin and calmodulin sequences revealed the presence of four species in the R. argillacea complex, of which two are newly described here: R. piperina sp. nov. and R. aegroticola sp. nov. In contrast to other related genera, all Rasamsonia species can be identified with ITS sequences. A retrospective identification was performed on the clinical isolates recently reported from animal or human patients. Susceptibility tests showed that the antifungal susceptibility profiles of the four members of the R. argillacea complex are similar and caspofungin showed significant activity in vitro, followed by amphotericin B and posaconazole. Voriconazole was the least active of the antifungals tested. The phenotypically similar species R. brevistipitata and R. cylindrospora had different antifungal susceptibility profiles and this indicates that correct species identification is important to help guide appropriate antifungal therapy.
    Journal of clinical microbiology 10/2012; · 4.16 Impact Factor
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    ABSTRACT: Aspergillus cibarius sp. nov. isolated from meju, a brick of dried fermented soybeans in Korea, is described. The species was also found from black bean, bread and salami in the Netherlands. It is characterized by abundant yellow to reddish brown ascomata and small lenticular ascospores (4.5-5.5 μm) with a wide furrow, low equatorial crests and tuberculate or reticulate convex surface. The species was resolved as phylogenetically distinct from the other reported Aspergillus species with an Eurotium teleomorph based on multilocus sequence typing using partial fragments of the β-tubulin, calmodulin, ITS and RNA polymerase II genes.
    The Journal of Microbiology 08/2012; 50(4):712-4. · 1.28 Impact Factor
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    ABSTRACT: Platypus cylindrus (Coleoptera: Curculionidae, Platypodidae) is an important insect pest of the cork oak. These beetles maintain symbiotic relationships with many fungi that serve especially as food for the adults and larvae but also intervene in the mechanisms of establishment of the insect by further weakening the host-tree. 270 samples were taken by 3 sources: Galleries (30), mycangia and intestinal contents of male and female insects and intestinal contents of mature larvae (60 each). The results show the presence of 42 species of ambrosia fungi among which 17 are new to this association. The mycetophagy of these beetles is very rich and consisted essentially of Ophiostomatales. Other groups of fungi playing different roles were also isolated: entomopathogenic, antagonistic, saprophytic but especially pathogenic for the tree host. This group consists of many species and their dissemination by the insect and the inoculation in trees may have fatal consequences by accelerating the cycle of declining affected trees. In the present paper, we discuss the fungal species associated to the beetle, identified on the basis of phenotypic characters and ribosomal DNA sequences analysis, and their relationship with P. cylindrus.
    African journal of microbiology research 11/2011; Vol. 5(25):4411-4423. · 0.54 Impact Factor
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    ABSTRACT: Wild type Aspergillus niger isolates from different biotopes from all over the world were compared to each other and to the type strains of other black Aspergillus species with respect to growth and extracellular enzyme profiles. The origin of the A. niger isolate did not result in differences in growth profile with respect to monomeric or polymeric carbon sources. Differences were observed in the growth rate of the A. niger isolates, but these were observed on all carbon sources and not specific for a particular carbon source. In contrast, carbon source specific differences were observed between the different species. Aspergillus brasiliensis is the only species able to grow on D-galactose, and A. aculeatus had significantly better growth on Locus Bean gum than the other species. Only small differences were found in the extracellular enzyme profile of the A. niger isolates during growth on wheat bran, while large differences were observed in the profiles of the different black aspergilli. In addition, differences were observed in temperature profiles between the black Aspergillus species, but not between the A. niger isolates, demonstrating no isolate-specific adaptations to the environment.These data indicate that the local environment does not result in stable adaptations of A. niger with respect to growth profile or enzyme production, but that the potential is maintained irrespective of the environmental parameters. It also demonstrates that growth, extracellular protein and temperature profiles can be used for species identification within the group of black aspergilli.
    Studies in Mycology 06/2011; 69(1):19-30. · 6.23 Impact Factor
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    ABSTRACT: Based on phylogenetic analysis of sequence data, Aspergillus section Usti includes 21 species, inclucing two teleomorphic species Aspergillus heterothallicus (= Emericella heterothallica) and Fennellia monodii. Aspergillus germanicus sp. nov. was isolated from indoor air in Germany. This species has identical ITS sequences with A. insuetusCBS 119.27, but is clearly distinct from that species based on β-tubulin and calmodulin sequence data. This species is unable to grow at 37 °C, similarly to A. keveii and A. insuetus. Aspergillus carlsbadensis sp. nov. was isolated from the Carlsbad Caverns National Park in New Mexico. This taxon is related to, but distinct from a clade including A. calidoustus, A. pseudodeflectus, A. insuetus and A. keveii on all trees. This species is also unable to grow at 37 °C, and acid production was not observed on CREA. Aspergillus californicus sp. nov. is proposed for an isolate from chamise chaparral (Adenostoma fasciculatum) in California. It is related to a clade including A. subsessilis and A. kassunensis on all trees. This species grew well at 37 °C, and acid production was not observed on CREA. The strain CBS 504.65 from soil in Turkey showed to be clearly distinct from the A. deflectus ex-type strain, indicating that this isolate represents a distinct species in this section. We propose the name A. turkensis sp. nov. for this taxon. This species grew, although rather restrictedly at 37 °C, and acid production was not observed on CREA. Isolates from stored maize, South Africa, as a culture contaminant of Bipolaris sorokiniana from indoor air in Finland proved to be related to, but different from A. ustus and A. puniceus. The taxon is proposed as the new species A. pseudoustus. Although supported only by low bootstrap values, F. monodii was found to belong to section Usti based on phylogenetic analysis of either loci BLAST searches to the GenBank database also resulted in closest hits from section Usti. This species obviously does not belong to the Fennellia genus, instead it is a member of the Emericella genus. However, in accordance with the guidelines of the Amsterdam Declaration on fungal nomenclature (Hawksworth et al. 2011), and based on phylogenetic and physiological evidence, we propose the new combination Aspergillus monodii comb. nov. for this taxon. Species assigned to section Usti can be assigned to three chemical groups based on the extrolites. Aspergillus ustus, A. granulosus and A. puniceus produced ustic acid, while A. ustus and A. puniceus also produced austocystins and versicolorins. In the second chemical group, A. pseudodeflectus produced drimans in common with the other species in this group, and also several unique unknown compounds. Aspergillus calidoustus isolates produced drimans and ophiobolins in common with A. insuetus and A. keveii, but also produced austins. Aspergillus insuetus isolates also produced pergillin while A. keveii isolates produced nidulol. In the third chemical group, E. heterothallica has been reported to produce emethallicins, 5'-hydroxyaveranthin, emeheterone, emesterones, 5'-hydroxyaveranthin.
    Studies in Mycology 06/2011; 69(1):81-97. · 6.23 Impact Factor
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    ABSTRACT: The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compel additional exploration. We therefore undertook whole-genome sequencing of the acidogenic A. niger wild-type strain (ATCC 1015) and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence, and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was used to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 Mb of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome analysis supported up-regulation of genes associated with biosynthesis of amino acids that are abundant in glucoamylase A, tRNA-synthases, and protein transporters in the protein producing CBS 513.88 strain. Our results and data sets from this integrative systems biology analysis resulted in a snapshot of fungal evolution and will support further optimization of cell factories based on filamentous fungi.
    Genome Research 06/2011; 21(6):885-97. · 14.40 Impact Factor
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    ABSTRACT: Aspergillus niger is perhaps the most important fungus used in biotechnology, and is also one of the most commonly encountered fungi contaminating foods and feedstuffs, and occurring in soil and indoor environments. Many of its industrial applications have been given GRAS status (generally regarded as safe). However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins: fumonisins and ochratoxins. In this study all available industrial and many non-industrial strains of A. niger (180 strains) as well as 228 strains from 17 related black Aspergillus species were examined for mycotoxin production. None of the related 17 species of black Aspergilli produced fumonisins. Fumonisins (B(2), B(4), and B(6)) were detected in 81% of A. niger, and ochratoxin A in 17%, while 10% of the strains produced both mycotoxins. Among the industrial strains the same ratios were 83%, 33% and 26% respectively. Some of the most frequently used strains in industry NRRL 337, 3112 and 3122 produced both toxins and several strains used for citric acid production were among the best producers of fumonisins in pure agar culture. Most strains used for other biotechnological processes also produced fumonisins. Strains optimized through random mutagenesis usually maintained their mycotoxin production capability. Toxigenic strains were also able to produce the toxins on media suggested for citric acid production with most of the toxins found in the biomass, thereby questioning the use of the remaining biomass as animal feed. In conclusion it is recommended to use strains of A. niger with inactive or inactivated gene clusters for fumonisins and ochratoxins, or to choose isolates for biotechnological uses in related non-toxigenic species such as A. tubingensis, A. brasiliensis, A vadensis or A. acidus, which neither produce fumonisins nor ochratoxins.
    PLoS ONE 01/2011; 6(8):e23496. · 3.53 Impact Factor
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    ABSTRACT: A novel species, Aspergillus brasiliensis sp. nov., is described within Aspergillus section Nigri. This species can be distinguished from other black aspergilli based on intergenic transcribed region, beta-tubulin and calmodulin gene sequences, by amplified fragment length polymorphism analysis and by extrolite profiles. A. brasiliensis isolates produced naphtho-gamma-pyrones, tensidol A and B and pyrophen in common with Aspergillus niger and Aspergillus tubingensis, but also several unique compounds, justifying their treatment as representing a separate species. None of the isolates were found to produce ochratoxin A, kotanins, funalenone or pyranonigrins. The novel species was most closely related to A. niger, and was isolated from soil from Brazil, Australia, USA and The Netherlands, and from grape berries from Portugal. The type strain of Aspergillus brasiliensis sp. nov. is CBS 101740(T) (=IMI 381727(T)=IBT 21946(T)).
    International journal of systematic and evolutionary microbiology 09/2007; 57(Pt 8):1925-32. · 2.11 Impact Factor
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    ABSTRACT: Species in the genus Aspergillus have been classified primarily based on morphological features. Sequencing of house-hold genes has also been used in Aspergillus taxonomy and phylogeny, while extrolites and physiological features have been used less frequently. Three independent ways of classifying and identifying aspergilli appear to be applicable: Morphology combined with physiology and nutritional features, secondary metabolite profiling and DNA sequencing. These three ways of identifying Aspergillus species often point to the same species. This consensus approach can be used initially, but if consensus is achieved it is recommended to combine at least two of these independent ways of characterising aspergilli in a polyphasic taxonomy. The chemical combination of secondary metabolites and DNA sequence features has not been explored in taxonomy yet, however. Examples of these different taxonomic approaches will be given for Aspergillus section Nigri.
    Studies in Mycology 02/2007; 59:31-7. · 6.23 Impact Factor
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    ABSTRACT: Aspergillus ustus is a very common species in foods, soil and indoor environments. Based on chemical, molecular and morphological data, A. insuetus is separated from A. ustus and revived. A. insuetus differs from A. ustus in producing drimans and ophiobolin G and H and not producing ustic acid and austocystins. The molecular, physiological and morphological data also indicated that another species, A. keveiisp. nov. is closely related but distinct from A. insuetus. Aspergillus section Usti sensu stricto includes 8 species: A. ustus, A. puniceus, A. granulosus, A. pseudodeflectus, A. calidoustus, A. insuetus and A. keveii together with Emericella heterothallica.
    Studies in Mycology 02/2007; 59:107-28. · 6.23 Impact Factor
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    ABSTRACT: The present taxonomy of the black aspergilli reveals that there are 19 accepted taxa. However the identification of species of Aspergillus section Nigri is often problematic in spite of the existence of numerous methods proposed. An overview is provided of phenotypic and molecular methods to identify the accepted species of the black aspergilli. Colony morphology, conidial size and ornamentation of the ex type cultures is presented in a pictorial overview. The temperature range of all species is given and their growth characteristics on creatine agar and boscalid agar, a medium which was developed as a selective medium for the isolation of A. carbonarius are also shown. The extrolites produced by each species are listed while the response of the Ehrlich reaction is described. The literature on the various molecular methods to be used for species identification is reviewed and a critical evaluation of the usefulness of various techniques and genomic loci for species identification of black aspergilli is presented.
    Studies in Mycology 02/2007; 59:129-45. · 6.23 Impact Factor
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    ABSTRACT: The genus Aspergillus is one of the most important filamentous fungal genera. Aspergillus species are used in the fermentation industry, but they are also responsible of various plant and food secondary rot, with the consequence of possible accumulation of mycotoxins. The aflatoxin producing A. flavus and A. parasiticus, and ochratoxinogenic A. niger, A. ochraceus and A. carbonarius species are frequently encountered in agricultural products. Studies on the biodiversity of toxigenic Aspergillus species is useful to clarify molecular, ecological and biochemical characteristics of the different species in relation to their different adaptation to environmental and geographical conditions, and to their potential toxigenicity. Here we analyzed the biodiversity of ochratoxin producing species occurring on two important crops: grapes and coffee, and the genetic diversity of A. flavus populations occurring in agricultural fields. Altogether nine different black Aspergillus species can be found on grapes which are often difficult to identify with classical methods. The polyphasic approach used in our studies led to the identification of three new species occurring on grapes: A. brasiliensis, A. ibericus, and A. uvarum. Similar studies on the Aspergillus species occurring on coffee beans have evidenced in the last five years that A. carbonarius is an important source of ochratoxin A in coffee. Four new species within the black aspergilli were also identified in coffee beans: A. sclerotioniger, A. lacticoffeatus, A. sclerotiicarbonarius, and A. aculeatinus. The genetic diversity within A. flavus populations has been widely studied in relation to their potential aflatoxigenicity and morphological variants L- and S-strains. Within A. flavus and other Aspergillus species capable of aflatoxin production, considerable diversity is found. We summarise the main recent achievements in the diversity of the aflatoxin gene cluster in A. flavus populations, A. parasiticus and the non-toxigenic A. oryzae. Studies are needed in order to characterise the aflatoxin biosynthetic genes in the new related taxa A. minisclerotigenes and A. arachidicola.
    Studies in Mycology 02/2007; 59:53-66. · 6.23 Impact Factor

Publication Stats

353 Citations
81.03 Total Impact Points

Institutions

  • 2011–2014
    • CBS Fungal Biodiversity Centre - Royal Netherlands Academy of Arts and Sciences
      Utrecht, Utrecht, Netherlands
  • 2007
    • National Research Council
      • Institute of Sciences of Food Production ISPA
      Roma, Latium, Italy
    • Technical University of Denmark
      • Center for Microbial Biotechnology
      Copenhagen, Capital Region, Denmark