Background Filamentous fungi have the ability to efficiently decompose plant biomass, and thus are widely used in the biofuel and bioprocess industries. In process, ambient pH has been reported to strongly affect the performance of the applied functional filamentous fungi. In this study, Trichoderma guizhouense NJAU4742 was investigated under the fermentation of rice straw at different initial pH values for a detailed study. Results The results showed that NJAU4742 strain could tolerate ambient pH values ranging from 3.0 to 9.0, but had significantly higher growth speed and extracellular enzyme activities under acidic conditions. At low ambient pH (< 4), NJAU4742 strain achieved rapid degradation of rice straw by elevating the ambient pH to an optimal range through environmental alkalinization. Further proteomic analysis identified a total of 1139 intracellular and extracellular proteins during the solid-state fermentation processes, including the quantified 190 carbohydrate-active enzymes (CAZymes) responsible for rice straw degradation, such as 19 cellulases, 47 hemicellulases and 11 chitinases. Meanwhile, the analysis results clearly showed that the secreted lignocellulases had a synergistic trend in distribution according to the ambient pH, and thus led to a pH-dependent classification of lignocellulases in T. guizhouense NJAU4742. Conclusions Most functional lignocellulases were found to be differently regulated by the ambient pH in T. guizhouense NJAU4742, which had the ability of speeding up biomass degradation by elevating the ambient pH through environmental alkalinization. These findings contribute to the theoretical basis for the biodegradation of plant biomass by filamentous fungi in the biofuel and bioprocess industries.

中文翻译：

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蛋白质组学分析反映了调节贵州木霉 NJAU4742 木质纤维素酶的环境碱化耦合 pH 依赖性机制。

背景丝状真菌具有高效分解植物生物质的能力，因此广泛用于生物燃料和生物加工工业。据报道，在处理过程中，环境 pH 值会强烈影响所应用的功能性丝状真菌的性能。本研究对贵州木霉NJAU4742在不同初始pH值的稻草发酵下进行了详细研究。结果结果表明，NJAU4742菌株能耐受3.0~9.0的环境pH值，但在酸性条件下生长速度和胞外酶活性显着提高。在低环境pH（< 4）下，NJAU4742菌株通过环境碱化将环境pH提高到最佳范围，实现了稻草的快速降解。进一步的蛋白质组学分析确定了固态发酵过程中总共 1139 种细胞内和细胞外蛋白质，包括量化的 190 种负责稻草降解的碳水化合物活性酶 (CAZymes)，例如 19 种纤维素酶、47 种半纤维素酶和 11 种几丁质酶。同时，分析结果清楚地表明，分泌的木质纤维素酶根据环境 pH 值具有协同分布的趋势，从而导致了贵州毛茛 NJAU4742 中木质纤维素酶的 pH 依赖性分类。结论 发现大多数功能性木质纤维素酶受环境 pH 值的不同调节，在 T. guizhouense NJAU4742 中具有通过环境碱化提高环境 pH 值来加速生物质降解的能力。