白腐真菌选择性降解苎麻秸秆木质素的分子机制研究

Selective ligninolysis is the limiting step in the comprehensive utilization process of the stalks which converted into feed, fertilizer and energy. White rot fungi are the only type of microorganisms that can degrade lignin completely. Two strains of selective ligninolysis (Ceriporiopsis subvermispora and Pleurotus ostreatus) and two non-selective strains (Phanerochaete chrysosporium and Trametes versicolor ) for ramie stalks have been screened in the previous experiments. Besides, the transcriptome of these four strains were also analyzed. The results showed that genes of cellulases, hemicellulases, pectinases and lignin-degrading enzymes were differentially expressed in four white-rot fungi. In this research, in order to provide insight into selective ligninolysis for ramie stalks from the protein level, iTRAQ-labeled method combined with LC-MS/MS was used to screen for the differentially expressed proteins of selective ligninolysis in four stains. Through starting correlation analysis of proteome and transcriptome (pervious foundation), searching and identifying new relative genes, proteins and signal pathways in selective degradation of lignin has been developed with the purpose of revealing molecular mechanism of selective ligninolysis in white-rot fungi. The results of this study will supply technical supports in developing new selective lignin-degrading enzyme systems and engineering strains and providing theoretical basis on comprehensive utilization process of the stalks and other straw resource utilization.

木质素选择性降解是秸秆饲料化、肥料化以及能源化等综合利用过程中的限速步骤。白腐真菌是目前所发现的唯一一类能彻底降解木质素的微生物。本项目前期研究筛选到了两株苎麻秸秆木质素选择性降解菌株（虫拟蜡菌和糙皮侧耳）和两株非选择性降解菌株（黄孢原毛平革菌和杂色栓菌)，并对这四种白腐真菌菌株的转录组进行了研究，结果表明四种菌株中纤维素酶、半纤维素酶、果胶酶以及木质素降解酶相关基因的表达存在显著差异。本项目为了从蛋白表达层面进一步了解苎麻秸秆木质素选择性降解分子机制，采用iTRAQ标记结合LC-MS/MS 质谱分析方法来探讨4个菌株中木质素降解相关蛋白的差异表达情况，对蛋白组和转录组（前期基础）开展关联分析，搜寻和鉴定新的与木质素选择性降解相关基因、蛋白及信号通路来揭示白腐菌选择性降解木质素的分子机理，为开发新型高效木质素选择性降解酶系和工程菌提供技术支持，为苎麻及其他作物秸秆资源化提供理论依据。

木质素选择性降解是秸秆饲料化、肥料化以及能源化等综合利用过程中的限速步骤。白腐真菌是目前所发现的唯一一类能彻底降解木质素的微生物。为了探讨木质素选择性降解的分子机制，本项目对两株苎麻秸秆木质素选择性降解菌株（虫拟蜡菌和糙皮侧耳）和两株非选择性降解菌株（黄孢原毛平革菌和杂色栓菌)的蛋白组进行了研究。采用iTRAQ标记结合LC-MS/MS 质谱分析方法来探讨4个菌株中木质素降解相关蛋白的差异表达情况，对蛋白组和转录组（前期基础）开展关联分析，搜寻和鉴定新的与木质素选择性降解相关蛋白。结果表明：纤维素酶、半纤维素酶和果胶酶在黄孢原毛平革菌和杂色栓菌中上调表达；木质素降解酶（包括漆酶和锰过氧化物酶）在虫拟蜡菌和糙皮侧耳中协调上调表达。酶活分析结果表明，黄孢原毛平革菌和杂色栓菌中羧甲基纤维素酶、滤纸酶和果胶酶活性显著高于虫拟蜡菌和糙皮侧耳；而虫拟蜡菌和糙皮侧耳中漆酶和锰过氧化物酶活性显著高于黄孢原毛平革菌和杂色栓菌。苎麻秸秆诱导下虫拟蜡菌和糙皮侧耳的胞外分泌蛋白组可以为开发新型高效木质素选择性降解酶系和工程菌提供技术支持，为苎麻及其他作物秸秆资源化提供理论依据。