海洋细菌CAZymes的研究进展

Research progress of carbohydrate-active enzymes on marine bacteria

多糖是大型藻类、浮游植物和微生物的主要成分,多糖降解产物是海洋有机物的主要来源。碳水化合物活性酶(carbohydrate-active enzymes,CAZymes)是负责糖类化合物降解、修饰及生成糖苷键的功能酶系,是糖类物质代谢通路中的基本功能单元。多数异养细菌都具备一套完善的碳水化合物活性酶编码系统,它们是参与碳水化合物降解的主要驱动力。基于碳水化合物活性酶的种类多样性、结构复杂性和功能特异性,我们对该家族的成员和作用机理还缺乏全局性了解。碳水化合物化学、分子生态学、微生物学和生物信息学的发展使人们对多糖的结构、细菌降解多糖的方式以及碳水化合物活性酶的作用机理有了新的认识。本次综述首先介绍了海洋环境中存在的多糖类别及相应的定性及定量分析方法;其次,总结了碳水化合物活性酶的新增成员以及数据库的现状,讨论了多糖利用位点(polysaccharide utilization loci,PULs)及几种海洋多糖降解的分子机制;最后,提出了一个基于多糖结构复杂性与细菌驱动的降解方式新模型,并对海洋细菌降解多糖与典型生态事件(如藻华)的关系进行了总结。论文旨在全局性地理解碳水化合物活性酶的分子功能与生态意义,为深入认识海洋环境中的碳水化合物代谢提供帮助。

Polysaccharides are the main components of macroalgae,phytoplankton,and microorganisms.Polysaccharide degradation products are the main source of marine organic matter.Carbohydrate-active enzymes(CAZymes),the typical functional enzymes for the degradation,modification,and generation of glycosidic bonds of carbohydrate compounds,are the basic functional units in carbohydrate metabolic pathways.Most heterotrophic bacteria are endowed with a complete CAZymes-encoding system,which is the main driving force for carbohydrate metabolism.However,owing to the diversity,complex structures,and functional specificity of CAZymes,there is a lack of a systematic understanding of the members in this family and the molecular mechanisms of action.The development of carbonhydrate chemistry,molecular ecology,microbiology,and bioinformatics allowed an in-depth understanding of the structures of polysaccharides,the degradation pathways,and the action mechanisms of the CAZymes.In this paper,the research advances of CAZymes were summarized.At first,this review introduced the types of polysaccharides in the marine environment and the corresponding methods of qualitative and quantitative analysis.Secondly,we summarized the latest progress of CAZymes and the database status and discussed polysaccharide utilization loci(PULs)and molecular degradation mechanisms of several marine polysaccharides.Finally,we presented a new conceptual model linking polysaccharide structural complexity to bacteria-driven polysaccharide utilization,and introduced the relationship between the polysaccharide degradation by heterotrophic bacteria and the algal bloom dynamics.The purpose of this paper is to enhance the systematic understanding of the molecular functions and ecological significance of CAZymes and deepen the understanding of carbohydrate metabolism in the marine environment.