Biomass-degrading enzymes with improved activity and stability can increase substrate saccharification and make biorefineries economically feasible. Filamentous fungi are a rich source of carbohydrate-active enzymes (CAZymes) for biomass degradation. The newly isolated LPH172 strain of the thermophilic Ascomycete Thielavia terrestris has been shown to possess high xylanase and cellulase activities and tolerate low pH and high temperatures. Here, we aimed to illuminate the lignocellulose-degrading machinery and novel carbohydrate-active enzymes in LPH172 in detail. We sequenced and analyzed the 36.6-Mb genome and transcriptome of LPH172 during growth on glucose, cellulose, rice straw, and beechwood xylan. 10,128 predicted genes were found in total, which included 411 CAZy domains. Compared to other fungi, auxiliary activity (AA) domains were particularly enriched. A higher GC content was found in coding sequences compared to the overall genome, as well as a high GC3 content, which is hypothesized to contribute to thermophilicity. Primarily auxiliary activity (AA) family 9 lytic polysaccharide monooxygenase (LPMO) and glycoside hydrolase (GH) family 7 glucanase encoding genes were upregulated when LPH172 was cultivated on cellulosic substrates. Conventional hemicellulose encoding genes (GH10, GH11 and various CEs), as well as AA9 LPMOs, were upregulated when LPH172 was cultivated on xylan. The observed co-expression and co-upregulation of genes encoding AA9 LPMOs, other AA CAZymes, and (hemi)cellulases point to a complex and nuanced degradation strategy. Our analysis of the genome and transcriptome of T. terrestris LPH172 elucidates the enzyme arsenal that the fungus uses to degrade lignocellulosic substrates. The study provides the basis for future characterization of potential new enzymes for industrial biomass saccharification.

中文翻译：

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嗜热木质纤维素降解真菌土生梭孢霉LPH172 的基因组和转录组学分析

具有改进活性和稳定性的生物质降解酶可以增加底物糖化并使生物精炼在经济上可行。丝状真菌是用于生物质降解的碳水化合物活性酶 (CAZymes) 的丰富来源。新分离的 LPH172 菌株嗜热子囊菌土生梭孢霉具有高木聚糖酶和纤维素酶活性，并能耐受低 pH 值和高温。在这里，我们旨在详细阐明 LPH172 中的木质纤维素降解机制和新型碳水化合物活性酶。我们对 LPH172 在葡萄糖、纤维素、稻草和山毛榉木聚糖上生长期间的 36.6 Mb 基因组和转录组进行了测序和分析。共发现10,128个预测基因，其中包括411个CAZy结构域。与其他真菌相比，辅助活动 (AA) 域特别丰富。与整个基因组相比，在编码序列中发现了更高的 GC 含量，以及高 GC3 含量，这被假设有助于嗜热性。当 LPH172 在纤维素基质上培养时，主要是辅助活性 (AA) 家族 9 裂解多糖单加氧酶 (LPMO) 和糖苷水解酶 (GH) 家族 7 葡聚糖酶编码基因上调。当在木聚糖上培养 LPH172 时，传统的半纤维素编码基因（GH10、GH11 和各种 CE）以及 AA9 LPMO 被上调。观察到的编码 AA9 LPMO、其他 AA CAZymes 和（半）纤维素酶的基因的共表达和共上调表明了一种复杂而微妙的降解策略。我们对 T 的基因组和转录组的分析。terrestris LPH172 阐明了真菌用来降解木质纤维素底物的酶库。该研究为未来表征用于工业生物质糖化的潜在新酶奠定了基础。