基于CAZymes生态多样性分析珠江口多糖与细菌的相互作用关系

源于海洋初级生产的多糖是细菌的重要碳源，细菌降解多糖是通过碳水化合物活性酶（CAZymes）介导的，近来发现海洋不同细菌的CAZymes组成与丰度有显著差异，存在“糖生态位”。然而，对富含多糖的河口细菌CAZymes生态多样性以及多糖对细菌群落的构建作用却知之甚少。本项目以珠江口为例，对水体和沉积物的细菌的CAZymes生态多样性进行研究。同时，通过加富培养实验，将不同性质的多糖添加到沉积物表层，重点研究沉积物中多糖与细菌相互关系。采用生物地球化学、分子生物学和宏基因组等技术，确定降解多糖优势菌群及其CAZymes酶家族的组成、丰度及变化特征，并结合多元统计学方法，分析环境因子与细菌群落组成和CAZymes多样性的相关性，揭示珠江口多糖对细菌CAZymes基因多态性的自然选择机制和对菌群结构调节规律。

Massive releases of organic substrates during marine algal blooms trigger growth of many clades of heterotrophic bacteria. Algal polysaccharides represent the most diverse and structurally complex class of these substrates.The enzymes that drive the synthesis and degradation of all the carbohydrates are named carbohydrate-active enzymes (CAZymes). Although partially studied on a distinct CAZymes patterns in bacteria on the taxonomic but also on the functional level during algal bloom from marine environments, diversity of microbial carbohydrate-active enzymes in estuary remain largely unknown. In this study, we will investegate the diversity of bacterial CAZymes associated with water and sediment samples from the Pearl River Estuary in situ. Focusing on the interaction between polysaccharides and bacteria, experiment will be performed by adding two different polysaccharides to the surface of sediment. We will compare metagenome-assembled genomes to identify the composition and dynamic changes of the dominant polysaccharide-degrading bacteria and their CAZymes. The relationship between environmental factors and bacterial community associated with CAZymes diversity will be analyzed with multivariate statistical methods. This study will reveal the natural selection mechanism of polysaccharide niches on bacterial CAZymes diversity and their forces on shaping the bacterial community structure.The results of the study will have important implications on an in-depth understanding of the carbon cycle in estuarine system.