黄翅大白蚁新型内源性木质纤维素降解酶性质与功能分析

纤维素是地球上含量最丰富的可再生资源，白蚁是木质纤维素的主要分解者之一，其肠道被誉为最小的生物反应器，研究白蚁木质纤维素酶系及其降解机制对生物质资源转化利用具有重要意义。黄翅大白蚁是我国南方常见高等培菌白蚁。早期研究认为培菌白蚁主要依靠体外共生真菌获取营养,利用真菌纤维素酶完成木质纤维素的消化。虽然近年来宏基因组研究发现后肠微生物蕴藏着丰富的水解酶基因，暗示肠道微生物在高等白蚁木质纤维素消化降解中发挥重要作用,但是有关高等白蚁肠道酶活性分布、转录组与蛋白组分析结果显示白蚁自身的木质纤维素酶系在其消化系统中可能发挥更大作用。本项目拟利用生化、分子生物学、比较转录组和蛋白组学方法研究黄翅大白蚁木质纤维素酶系，通过新型内源性酶的纯化、基因克隆和转录分析，确定基因体内表达位点，鉴定重组酶的性质和功能，从而揭示内源性酶在高等白蚁木质纤维素降解中的作用，加深对高等白蚁木质纤维素降解机制的认识和理解。

Cellulose on earth is the most abundant renewable resources. Termite is one of the main decomposers of lignocelluloses and the gut of termite is regarded as the smallest bioreactor. Understanding of lignocellulosic enzymes and degradation mechanism of the termite is very important to the biomass conversion and utilization. Macrotermes barneyi is a fungus-grown termite and is commonly found in Southern China. Early studies suggested that M. barneyi mainly relies on symbiotic fungi for nutrition and to obtain cellulases to complete the digestion of lignocellulose. Although recent studies on microbial metagenomics of termite revealed that the hindgut is rich in glycoside hydrolase genes, suggesting that the intestinal microflora in higher termites play an important role in the lignocelluloses digestion, the results about the distribution of gut activity in higher termite and the transcriptome, proteomic data have indicated that termites endogenous lignocelluosic enzymes might play a more important role in their digestive system. In order to reveal the role of endogenous enzymes in lignocelluloses degradation in the high termites, this project will use biochemistry, molecular biology, comparative transcriptomics and proteomics approaches to purify novel endogenous lignocellulosic enzymes from the M.barneyi, clone the cDNA and determine the in vivo expression sites. Further, heterologous expression and characterization of the function of enzymes will be also performed. The study is expected to deepen our understanding of lignocelluloses degradation mechanism of high termites.