黄渤海海草分布区日本鳗草根际微生物群落结构特征及其功能分析

Rhizosphere microbial community structure and function of Zostera japonica in the distribution area of seagrass beds in the Yellow Sea and Bohai Sea

摘要:

日本鳗草（Zostera japonica）是亚洲特有的海草种类，具有重要生态价值。近年来，黄渤海海草分布区中的日本鳗草海草床持续退化，引起了研究人员的广泛关注。[目的]基于根际微生物的分布与日本鳗草的健康生长密切相关的设想，本文旨在探究黄渤海海草分布区日本鳗草根际细菌群落结构多样性并分析其与海草健康生长的内在联系。[方法]选取黄渤海海草分布区中东营、威海、大连3个地点的日本鳗草根际与非草区表层沉积物，采用高通量测序技术（Illumina HiSeq PE300）解析根际微生物群落特征，并结合相关环境参数分析其环境功能。[结果]日本鳗草根际表层沉积物中主要存在的细菌类群有：变形菌门（Proteobacteria）所占比例为41.1%，蓝细菌门（Cyanobacteria）占15.4%，拟杆菌门（Bacteroidetes）占12.6%，放线菌门（Actinobacteria）占9.3%。不同地点之间以及样品类型（海草床根际与非根际）之间的微生物群落存在显著差异，主要表现为根际富含硫酸盐还原菌和固氮菌。环境因素：TN（total nitrogen）、TC（total carbon）、TOC（total organic carbon）、黏土（Clay）、砷（As）与根际群落组成与分布显著相关。[结论]从功能的角度来看，不同地点、不同样品类型之间的差异物种多与硫、氮代谢相关，硫酸盐还原菌对维持日本鳗草的生态健康起关键作用；日本鳗草根际微生物群落分布与环境因子、空间分布有一定相关性。

Abstract:

Zostera japonica is a unique Asian seaweed species and has important ecological value. In recent years, Zostera japonica has been continuing to degenerate, causing widespread concern among researchers. [Objective] We hypothesized that the rhizospheric microorganisms were closely related with the healthy growth of Zostera japonica. We explored the diversity and function of microbial community in root of Zostera japonica at coastal zone of Yellow sea and Bohai sea, and intrinsic relationship with seagrass.[Methods] We collected surface sediment samples of Zostera japonica roots and unvegetated areas from three locations including Dongying, Weihai, and Dalian city. We investigated the rhizosphere microbial community structure by sequencing on Illumina HiSeq300 platform and analyzed the correlation between microbial community structure and environmental parameters. [Results] The most dominated phyla widely distributed in the rhizospheric surface sediments of Zostera japonica included:Proteobacteria (41.1%), Cyanobacteria (15.4%), Bacteroidetes (12.6%), Actinobacteria (9.3%). Comparisons of different regions (Weihai, Dongying, and Dalian) or sample types (rhizosphere vs. non-rhizosphere) showed significant differences in microbial communities, mainly due to the presence of sulfate-reducing bacteria and nitrogen-fixing bacteria found in the rhizosphere. Total nitrogen, total carbon, total organic carbon, clay, were all significantly correlated to rhizospheric bacterial community composition and distribution. [Conclusion] From a functional point of view, the differences between groups was mostly related to sulfur and nitrogen cycling, and sulfate reducing bacteria play a key role in maintaining the ecological health of Zostera japonica.