The genome of Schizophyllum commune encodes a diverse repertoire of degradative enzymes for plant cell wall breakdown. Recent comparative genomics study suggests that this wood decayer likely has a mode of biodegradation distinct from the well-established white-rot/brown-rot models. However, much about the extracellular enzyme system secreted by S. commune during lignocellulose deconstruction remains unknown and the underlying mechanism is poorly understood. In this study, extracellular proteins of S. commune colonizing Jerusalem artichoke stalk were analyzed and compared with those of two white-rot fungi Phanerochaete chrysosporium and Ceriporiopsis subvermispora and a brown-rot fungus Gloeophyllum trabeum. Under solid-state fermentation (SSF) conditions, S. commune displayed considerably higher levels of hydrolytic enzyme activities in comparison with those of P. chrysosporium, C. subvermispora and G. trabeum. During biodegradation process, this fungus modified the lignin polymer in a way which was consistent with a hydroxyl radical attack, similar to that of G. trabeum. The crude enzyme cocktail derived from S. commune demonstrated superior performance over a commercial enzyme preparation from Trichoderma longibrachiatum in the hydrolysis of pretreated lignocellulosic biomass at low enzyme loadings. Secretomic analysis revealed that compared with three other fungi, this species produced a higher diversity of carbohydrate-degrading enzymes, especially hemicellulases and pectinases acting on polysaccharide backbones and side chains, and a larger set of enzymes potentially supporting the generation of hydroxyl radicals. In addition, multiple non-hydrolytic proteins implicated in enhancing polysaccharide accessibility were identified in the S. commune secretome, including lytic polysaccharide monooxygenases (LPMOs) and expansin-like proteins. Plant lignocellulose degradation by S. commune involves a hydroxyl radical-mediated mechanism for lignocellulose modification in parallel with the synergistic system of various polysaccharide-degrading enzymes. Furthermore, the complex enzyme system of S. commune holds significant potential for application in biomass saccharification. These discoveries will help unveil the diversity of natural lignocellulose-degrading mechanisms, and advance the design of more efficient enzyme mixtures for the deconstruction of lignocellulosic feedstocks.

Microbial consortia represent promising candidates for aiding in the development of plant biomass conversion strategies for biofuel production. However, the interaction between different community members and the dynamics of enzyme complements during the lignocellulose deconstruction process remain poorly understood. We present here a comprehensive study on the community structure and enzyme systems of a lignocellulolytic microbial consortium EMSD5 during growth on corn stover, using metagenome sequencing in combination with quantitative metaproteomics. The taxonomic affiliation of the metagenomic data showed that EMSD5 was primarily composed of members from the phyla Proteobacteria, Firmicutes and Bacteroidetes. The carbohydrate-active enzyme (CAZyme) annotation revealed that representatives of Firmicutes encoded a broad array of enzymes responsible for hemicellulose and cellulose deconstruction. Extracellular metaproteome analysis further pinpointed the specific role and synergistic interaction of Firmicutes populations in plant polysaccharide breakdown. In particular, a wide range of xylan degradation-related enzymes, including xylanases, β-xylosidases, α-l-arabinofuranosidases, α-glucuronidases and acetyl xylan esterases, were secreted by diverse members from Firmicutes during growth on corn stover. Using label-free quantitative proteomics, we identified the differential secretion pattern of a core subset of enzymes, including xylanases and cellulases with multiple carbohydrate-binding modules (CBMs). In addition, analysis of the coordinate expression patterns indicated that transport proteins and hypothetical proteins may play a role in bacteria processing lignocellulose. Moreover, enzyme preparation from EMSD5 demonstrated synergistic activities in the hydrolysis of pretreated corn stover by commercial cellulases from Trichoderma reesei. These results demonstrate that the corn stover-adapted microbial consortium EMSD5 harbors a variety of lignocellulolytic anaerobic bacteria and degradative enzymes, especially those implicated in hemicellulose decomposition. The data in this study highlight the pivotal role and cooperative relationship of Firmicutes members in the biodegradation of plant lignocellulose by EMSD5. The differential expression patterns of enzymes reveal the strategy of sequential lignocellulose deconstruction by EMSD5. Our findings provide insights into the mechanism by which consortium members orchestrate their array of enzymes to degrade complex lignocellulosic biomass.

Microbial communities that inhabit the host's intestine influence many aspects of the host's health and bear the adaptive potential to alterations in harsh environments and diets. The Qinghai‐Tibet Plateau represents one of the harshest environments in the world. Preliminary progress has been made in identifying the communities of gut microbes in Indigenous Tibetans and non‐human animals. However, due to the complexity of microbial communities, the effects of gut microbes on the host's health and high‐plateau adaptation remain unexplained. Herein, we review the latest progress in identifying factors affecting the gut microbiota of native Tibetans and non‐human animals and highlight the complex interactions between the gut microbiota, health and highland adaptation, which provides a basis for exploring the correlations between the gut microbiota and clinical indexes in native highland residents and travellers, as well as developing microbiota‐based strategies to mitigate health risks for tourists and treatments for mountain sickness during high‐altitude travel in the future.