Biodegradation is the key process involved in natural lignocellulose biotransformation and utilization. Microbial consortia represent promising candidates for applications in lignocellulose conversion strategies for biofuel production; however, cooperation among the enzymes and the labor division of microbes in the microbial consortia remains unclear. In this study, metagenomic analysis was performed to reveal the community structure and extremozyme systems of a lignocellulolytic microbial consortium, TMC7. The taxonomic affiliation of TMC7 metagenome included members of the genera Ruminiclostridium (42.85%), Thermoanaerobacterium (18.41%), Geobacillus (10.44%), unclassified_f__Bacillaceae (7.48%), Aeribacillus (2.65%), Symbiobacterium (2.47%), Desulfotomaculum (2.33%), Caldibacillus (1.56%), Clostridium (1.26%), and others (10.55%). The carbohydrate-active enzyme annotation revealed that TMC7 encoded a broad array of enzymes responsible for cellulose and hemicellulose degradation. Ten GHs endoglucanase, 4 GHs exoglucanase, and 6 GHs β-glucosidase were identified for cellulose degradation; 6 GHs endo-β-1,4-xylanase, 9 GHs β-xylosidase, and 3 GHs β-mannanase were identified for degradation of the hemicellulose main chain; 6 GHs arabinofuranosidase, 2 GHs α-mannosidase, 11 GHs galactosidase, 3 GHs α-rhamnosidase, and 4 GHs α-fucosidase were identified as xylan debranching enzymes. Furthermore, by introducing a factor named as the contribution coefficient (CC), we found that Ruminiclostridium and Thermoanaerobacterium may be the dominant contributors, whereas Symbiobacterium and Desulfotomaculum may serve as "sugar cheaters," in lignocellulose degradation by TMC7. Our findings provide mechanistic profiles of an array of enzymes that degrade complex lignocellulosic biomass in the microbial consortium TMC7 and provide a promising approach for studying the potential contribution of microbes in microbial consortia.

中文翻译：

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对嗜热微生物群 TMC7 木质纤维素降解的宏基因组洞察。

生物降解是天然木质纤维素生物转化和利用的关键过程。微生物聚生体代表了在生物燃料生产的木质纤维素转化策略中应用的有前途的候选者；然而，酶之间的合作以及微生物群落中微生物的分工仍不清楚。在这项研究中，进行了宏基因组分析以揭示木质纤维素分解微生物群落 TMC7 的群落结构和极酶系统。TMC7 宏基因组的分类隶属包括瘤胃梭菌属( 42.85%)、热厌氧杆菌属(18.41%)、地杆菌属(10.44%)、未分类_f__芽孢杆菌属(7.48%)、产气杆菌属(2.65%) 的成员，共生菌(2.47%)、脱硫菌(2.33%)、钙杆菌(1.56%)、梭菌(1.26%)，以及其他 (10.55%)。碳水化合物活性酶注释表明，TMC7 编码了一系列负责纤维素和半纤维素降解的酶。鉴定了 10 种 GHs 内切葡聚糖酶、4 种 GHs 外切葡聚糖酶和 6 种 GHs β-葡萄糖苷酶用于纤维素降解；鉴定出 6 种 GHs 内切-β-1,4-木聚糖酶、9 种 GHs β-木糖苷酶和 3 种 GHs β-甘露聚糖酶可降解半纤维素主链；6 GHs 阿拉伯呋喃糖苷酶、2 GHs α-甘露糖苷酶、11 GHs 半乳糖苷酶、3 GHs α-鼠李糖苷酶和 4 GHs α-岩藻糖苷酶被鉴定为木聚糖脱支酶。此外，通过引入一个名为贡献系数（CC）的因素，我们发现瘤胃梭菌和热厌氧杆菌可能是主要贡献者，而在TMC7降解木质纤维素的过程中，共生杆菌和Desulfotomaculum可能充当“糖欺骗者”。我们的研究结果提供了一系列酶的机理概况，这些酶可降解微生物群落 TMC7 中的复杂木质纤维素生物质，并为研究微生物在微生物群落中的潜在贡献提供了一种有前途的方法。