南海环境微生物对聚球藻有机物质的响应

The responses of environmental microbes from the South China Sea to Synechococcus-derived organic matter addition

摘要:

【背景】海洋浮游植物产生的有机物质与异养细菌之间的相互作用是上层海洋物质和能量循环过程中的重要组成部分。【目的】探究寡营养海域微生物群落对聚球藻有机物(Synechococcus- derived organic matter，SOM)的响应和代谢利用过程，加深对海洋微生物介导的生物地球化学循环过程的认识。【方法】利用南海海域微生物群落，添加聚球藻有机物质后黑暗培养，对培养过程中有机碳、营养盐和活性微生物群落结构的变化进行追踪。【结果】在短期的培养过程中，有60%?73%的SOM被微生物所利用。γ-变形菌(Gammaproteobacteria)在培养过程中响应最快，也是最优势微生物类群。SOM的加入改变了原位微生物群落结构，并且随着活性有机物质逐步被消耗，微生物群落结构也发生了演替。【结论】SOM中的大部分物质都属于活性有机物质，可以快速地被微生物所降解利用。不同微生物类群响应不同生物可利用性有机物质，推动了海洋物质和能量的循环。

关键词:南海，聚球藻有机物质，异养细菌

Abstract:

[Background] The interaction between marine phytoplankton-derived organic matter and heterotrophic bacteria is an important part of biogeochemistry cycle in the upper ocean. [Objective] Studying the responses of microbial communities in oligotrophic environment to Synechococcus-derived organic matter (SOM) could increase our understanding of marine biogeochemistry cycle. [Methods] A SOM-addition incubation experiment was conducted in the South China Sea, and the variations of organic carbon, nutrients, and active microbial communities were monitored during the incubation. [Results] During the short-term incubations, 60%–73% of SOM was utilized by microbes. Gammaproteobacteria was the fastest responder, and the most dominant microbial population over the entire incubations. The addition of SOM changed the in situ microbial community structure, and the succession of microbial community structure was also observed corresponding the consumption of labile organic matter. [Conclusion] Most of the SOM belong to labile organic matter which could be quickly degraded and utilized by heterotrophic bacteria. Microbes could respond positively to phytoplankton-derived fresh organic matter, and their activities drive the biogeochemistry cycle in the ocean.

Key words:The South China Sea, Synechococcus-derived organic matter, Heterotrophic bacteria