藻际环境中胞外聚合物的研究进展

Advances in extracellular polymeric substances in phycosphere environment

微藻向细胞周围释放营养物质而形成了独特的藻际微环境,吸引了大量细菌的定殖。藻际环境中藻菌关系错综复杂,其间充斥着多样的物质交换与信息交流。以胞外聚合物(extracellularpolymeric substances,EPS)为代表的有机质在其中起着纽带作用。微藻和细菌都可以产生EPS,其过程受多种因素的调节。EPS在藻际环境中具有重要的生态功能,包括参与生物被膜(biofilm)的形成,影响藻菌共生关系的建立以及调节藻际微生物群落组成等。此外,EPS中的一大类别透明胞外聚合物颗粒(transparent exopolymer particles,TEP)还介导了海洋溶解有机碳向颗粒有机碳的转化,参与了海洋碳循环过程。本文以EPS的产生、组成以及对碳转化的影响为重点,综述了其在藻际生态位(Niche)中的生态功能,以期为深入理解藻际环境中的有机质特征和藻菌共生关系提供理论依据。

Microalgae releases extracellular substances around the cell to form a unique algal microenvironment called"phycosphere niche"that attracts a large number of bacteria to colonize.The algae-bacteria interactions are very complex involving multiply material exchanges and information communication.Among the algae-bacterial relationship,extracellular polymeric substances(EPS)serve as a bridge for matter flux.Both microalgae and bacteria can produce EPS,and the production process is regulated by many factors.In the phycosphere environment,EPS play important ecological roles,such as participating in the formation of biofilm,affecting the algae-bacterial symbiotic structure and regulating the composition of microbial communities.In addition,as an important member of EPS,transparent exopolymer particles(TEP)mediate the conversion of dissolved organic carbon into particulate organic carbon.This profile made TEP is an important regulator,participating in marine carbon cycle.In this review,we focus on phycosphere niche,and summarise the newest advance in EPS production,composition and effect factors.Meanwhile,the ecological roles of EPS in marine carbon cycle have also been discussed,to provide reference for better understanding the organic matter properties and algae-bacterial behavior in the phycosphere environment.