海洋浮游植物胞外多聚物的研究进展

海洋中胞外多聚物（extracellular polymeric substances，EPS）是一类富含碳的黏性物质，由酸性多糖组成，主要由浮游植物产生。EPS主要分为三类:细胞涂层EPS、溶解性EPS和透明胞外聚合颗粒物（transparent exopolymer particles，TEP）。EPS本身呈溶解态，属于溶解有机碳库；但EPS可通过凝结或起泡方式转换形成颗粒态的TEP，属于颗粒有机碳库。EPS能被微生物降解或吸收，直接参与微食物环的碳循环。颗粒态的TEP可聚集生物有机颗粒形成"海洋雪"，加快有机碳的沉降。因此EPS成为连接溶解态和颗粒态有机碳的桥梁，有效改变了海洋生态系统中有机碳库的分配，在塑造海洋生态系统结构和功能中具有重要地位。本文从EPS的特点、形成机制、对细胞积聚和海洋碳循环的影响等方面综述了目前EPS的研究进展。

A review of extracellular polymeric substances(EPS)by marine phytoplankton

The extracellular polymeric substances(EPS), a class of sticky material with high concentration of carbon, is consists of acidic polysaccharides.EPS is mainly produced by phytoplankton in marine environment.EPS is grouped generally into three categories:EPS cell coating, soluble EPS, and transparent exopolymer particles (TEP).EPS can dissolve in the water column, belonging to the dissolved organic carbon pool.However, EPS can form TEP of particles, belonging to the particulate organic carbon pool, via coagulate or bubbling.EPS can be absorbed or degraded by microorganisms and thus directly involve in carbon cycle within microbial loop.TEP can form marine snow by aggregating bio-organic particles, accelerating the sinking of organic carbon.Therefore, EPS is the bridge of dissolved organic carbon and particulate organic carbon, and plays key roles in shaping of the structure and function of in the marine ecosystems.This paper overviewed the current research progress of EPS, including, characteristics, formation mechanism, impact on the accumulation of cells and the contribution to the marine carbon cycle.