Early-branching gut fungi possess a large, comprehensive array of biomass-degrading enzymes

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Science  11 Mar 2016:
Vol. 351, Issue 6278, pp. 1192-1195
DOI: 10.1126/science.aad1431

Mining gut fungi to break down biomass

The recalcitrance of plant biomass remains a formidable bottleneck in the production of biofuels and other chemicals from renewable sources. Enzymes from microbial communities found within ruminants and hindgut fermenters, however, show considerable promise to break down plant material into simple sugars efficiently. Solomon et al. used 'omics-level and biochemical assays to reveal a suite of lignocellulose-degrading enzymes from early-diverging anaerobic fungi isolated from the guts of horses, goats, and sheep. This approach not only reveals the regulation of these pathways but also represents a method to identify enzymes with no known homologs that would be unidentifiable using conventional screening methods.

Science, this issue p. 1192


The fungal kingdom is the source of almost all industrial enzymes in use for lignocellulose bioprocessing. We developed a systems-level approach that integrates transcriptomic sequencing, proteomics, phenotype, and biochemical studies of relatively unexplored basal fungi. Anaerobic gut fungi isolated from herbivores produce a large array of biomass-degrading enzymes that synergistically degrade crude, untreated plant biomass and are competitive with optimized commercial preparations from Aspergillus and Trichoderma. Compared to these model platforms, gut fungal enzymes are unbiased in substrate preference due to a wealth of xylan-degrading enzymes. These enzymes are universally catabolite-repressed and are further regulated by a rich landscape of noncoding regulatory RNAs. Additionally, we identified several promising sequence-divergent enzyme candidates for lignocellulosic bioprocessing.

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