Insect fungal symbionts: A promising source of detoxifying enzymes

Journal of Industrial Microbiology and Biotechnology (Impact Factor: 2.32). 04/1992; 9(3):149-161. DOI: 10.1007/BF01569619
Source: OAI

ABSTRACT Many species of insects cultivate, inoculate, or contain symbiotic fungi. Insects feed on plant materials that contain plant-produced defensive toxins, or are exposed to insecticides or other pesticides when they become economically important pests. Therefore, it is likely that the symbiotic fungi are also exposed to these toxins and may actually contribute to detoxification of these compounds. Fungi associated with bark beetles, ambrosia beetles, termites, leaf-cutting ants, long-horned beetles, wood wasps, and drug store beetles can variously metabolize/detoxify tannins, lignins, terpenes, esters, chlorinated hydrocarbons, and other toxins. The fungi (Attamyces) cultivated by the ants and the yeast (Symbiotaphrina) contained in the cigarette beetle gut appear to have broad-spectrum detoxifying abilities. The present limiting factor for using many of these fungi for large scale detoxification of, for example, contaminated soils or agricultural commodities is their slow growth rate, but conventional strain selection techniques or biotechnological approaches should overcome this problem.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Hunt bumble bee (Bombus huntii Greene, Hymenoptera: Apidae) is a holometabolous, social insect important as a pollinator in natural and agricultural ecosystems in western North America. Bumble bees spend a significant amount of time foraging on a wide variety of flowering plants, and this activity exposes them to both plant toxins and pesticides, posing a threat to individual and colony survival. Little is known about what detoxification pathways are active in bumble bees, how the expression of detoxification genes changes across life stages, or how the number of detoxification genes expressed in B. huntii compares to other insects. We found B. huntii expressed at least 584 genes associated with detoxification and stress responses. The expression levels of some of these genes, such as those encoding the cytochrome P450s, glutathione S-transferases (GSTs) and glycosidases, vary among different life stages to a greater extent than do other genes. We also found that the number of P450s, GSTs and esterase genes expressed by B. huntii is similar to the number of these genes found in the genomes of other bees, namely Bombus terrestris, Bombus impatiens, Apis mellifera and Megachile rotundata, but many fewer than are found in the fly Drosophila melanogaster. Bombus huntii has transcripts for a large number of detoxification and stress related proteins, including oxidation and reduction enzymes, conjugation enzymes, hydrolytic enzymes, ABC transporters, cadherins, and heat shock proteins. The diversity of genes expressed within some detoxification pathways varies among the life stages and castes, and we typically identified more genes in the adult females than in larvae, pupae, or adult males, for most pathways. Meanwhile, we found the numbers of detoxification and stress genes expressed by B. huntii to be more similar to other bees than to the fruit fly. The low number of detoxification genes, first noted in the honey bee, appears to be a common phenomenon among bees, and perhaps results from their symbiotic relationship with plants. Many flowering plants benefit from pollinators, and thus offer these insects rewards (such as nectar) rather than defensive plant toxins.
    BMC Genomics 12/2013; 14(1):874. · 4.40 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study investigated the diversity of yeasts involved in intestinal tract of higher termite M. subhyalinus from Côte d’Ivoire. Yeasts were absent from the digestive tract of soldiers and present in the worker termites at a load of 2.1 x 105 UFC/mL. Initial molecular identification to the species level was carried out using RFLP of PCR-amplified internal transcribed spacers of rDNA (ITS1-5.8S-ITS4). Three different profiles were obtained from the restriction of PCR products with the seven endonucleases Hae III, Hinf I, Pvu II, Alu I, Xho I, BamH I and Msp I. Sequence analysis of the ITS regions allowed us to assign these groups to two different species: Pichia kudriavzevii and Candida tropicalis. P. kudriavzevii was the most commonly species isolated (84.60%). Two genotypic strains were found for this species. The first one (Ia) gave three restriction bands with endonucleases Hae III and Xho I while the second one (Ib) gave two bands and one band respectively with the same enzymes. In addition, these strains showed four and two nucleotides divergence from a reference strains. The sequence data obtained from the PCR products were aligned and compared with other sequences. Homologous sequences of fungi were obtained from GenBank database.
    International Journal of Advanced Research 01/2014; 2(8):139. · 1.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Asian longhorned beetle (Anoplophoraglabripennis) is an invasive, wood-boring pest that thrives in the heartwood of deciduous tree species. A large impediment faced by A. glabripennis as it feeds on woody tissue is lignin, a highly recalcitrant biopolymer that reduces access to sugars and other nutrients locked in cellulose and hemicellulose. We previously demonstrated that lignin, cellulose, and hemicellulose are actively deconstructed in the beetle gut and that the gut harbors an assemblage of microbes hypothesized to make significant contributions to these processes. While lignin degrading mechanisms have been well characterized in pure cultures of white rot basidiomycetes, little is known about such processes in microbial communities associated with wood-feeding insects. The goals of this study were to develop a taxonomic and functional profile of a gut community derived from an invasive population of larval A. glabripennis collected from infested host trees and to identify genes that could be relevant for the digestion of woody tissue and nutrient acquisition. To accomplish this goal, we taxonomically and functionally characterized the A. glabripennis midgut microbiota through amplicon and shotgun metagenome sequencing and conducted a large-scale comparison with the metagenomes from a variety of other herbivore-associated communities. This analysis distinguished the A. glabripennis larval gut metagenome from the gut communities of other herbivores, including previously sequenced termite hindgut metagenomes. Genes encoding enzymes were identified in the A. glabripennis gut metagenome that could have key roles in woody tissue digestion including candidate lignin degrading genes (laccases, dye-decolorizing peroxidases, novel peroxidases and β-etherases), 36 families of glycoside hydrolases (such as cellulases and xylanases), and genes that could facilitate nutrient recovery, essential nutrient synthesis, and detoxification. This community could serve as a reservoir of novel enzymes to enhance industrial cellulosic biofuels production or targets for novel control methods for this invasive and highly destructive insect.
    PLoS ONE 01/2013; 8(9):e73827. · 3.53 Impact Factor


Available from