共生细菌在象白蚁木质纤维素降解过程中的作用与机理研究

木食性白蚁与其肠道微生物的共生关系是自然界生物共生的典型例子。然而，迄今为止人们对共生微生物协助白蚁降解木质纤维素的机制鲜有认识。象白蚁是一类能高效降解木质纤维素的高等木食性白蚁，是研究微生物与白蚁共生机制的良好模型。本项目拟在对海南象白蚁肠道共生细菌初步研究基础上，应用电镜、分析化学和高通量测序等技术研究木质纤维素在象白蚁肠道不同部位物态变化、代谢产物与共生细菌菌群结构之间的相关性，探讨共生细菌在木质纤维素降解过程中的作用。同时，模拟肠道理化条件分离纯化丝状杆菌、拟杆菌等优势共生细菌，对分离菌进行理化特征、代谢途径和纤维素降解活性等功能分析。采用原位杂交和荧光定量PCR等技术对分离菌进行定位和定量，为阐明共生细菌在象白蚁木质纤维素降解过程中的作用与机理提供证据。本项目对深入解析木食性白蚁与肠道微生物共生关系的本质具有重要的科学意义。

The symbiotic association between wood-feeding termites and their intestinal microbiota is a typical symbiosis system in nature. However, so far our understanding of the mechanisms of the symbiotic microbiota in lignocellulose degradation is poor. Nasutitermes is a kind of wood-feeding higher termite that can degrade lignocellulose efficiently, which is a good model for the study of symbiotic relationships between termites and their intestinal microbiota. Based on primary studies on the symbiotic bacteria of Nasutitermes sp., in this project, we will use electromicroscopy, analytical chemistry techniques and high-throughput sequencing techniques to study the relationships among the physical status of lignocellulose, metabolic intermediates and symbiotic bacterial community structures of different intestinal compartments of Nasutitermes sp., in order to understand the roles of symbiotic bacteria in the process of lignocellulose degradation. In the meantime, we will isolate and purify dominant bacteria like Fibrobacteres and Bacteroides with different methods and techniques and analyze the physiochemical characteristics, metabolic pathways and cellulolytic capabilities of these isolates. Fluorescence in situ hybridization and quantitative real-time PCR will be used to localize and quantify major bacterial isolates. All these studies will give evidence for the understanding of the functions and mechanisms of symbiotic bacteria in the gut of Nasutitermes in the process of cellulose degradation. This project will make great scientific significance in the elucidation of the essence of the symbiotic association between wood-feeding termites and their intestinal microbiota.