渤海湾湾口表层沉积物中的核心细菌群落结构及其对环境因子的响应

Structure characteristics of core bacterial communities in surface sediments and analysis on their responses to environmental factors in the inlet of Bohai Bay

摘要:

【背景】近年来渤海湾环境恶化加重，影响了近海生态系统的可持续发展。微生物对环境的高度灵敏性使其能够迅速对环境的变更做出反应，在海洋能量流动与物质循环过程中发挥了无可替代的作用。【目的】为探讨渤海湾湾口沉积物中细菌群落分布特征及其对环境因子的响应，选取渤海湾湾口21个站位的表层沉积物样品进行探究。【方法】利用高通量测序技术(Illumina HiSeq 2500)对细菌16S rRNA基因V3?V4高变区进行测序，并结合相关环境因子分析沉积物中细菌群落组成和空间分布特征，试图探究起驱动作用的主要环境因子。【结果】研究区域广泛存在的细菌类群包括：变形菌门(Proteobacteria)占56.8%，酸杆菌门(Acidobacteria)占8.9%，绿弯菌门(Chloroflexi)占8.1%，拟杆菌门(Bacteroidetes)占6.2%，其中γ-变形菌纲(Gamma-proteobacteria)和δ-变形菌纲(Delta-proteobacteria)为变形菌门中的优势类群。陆源有机物的输入使入海口及近岸处总有机碳(Total organic carbon，TOC)、总有机氮(Total organic nitrogen，TON)含量偏高，并向周围呈辐射状降低，低值位于渤海湾中部深水区域。通过冗余性分析(Redundancy analysis，RDA)发现在研究区域中环境因素对物种组成和群落结构具有显著影响，其中粒径(<4 μm)和有机氮的影响较大(P<0.05)。【结论】渤海湾微生物物种丰富，与环境因素关系显著，人为因素对微生物多样性和群落结构组成具有重要的影响作用。

关键词:渤海湾，沉积物，微生物群落，16S rRNA基因多样性

Abstract:

[Background] In recent years, the increasingly polluted environment of Bohai Bay has impacted the sustainability of offshore ecosystems. [Objective] To explore the distribution characteristics of bacterial communities in surface sediments and their response to environmental factors, we selected surface sediment samples from 21 stations for study. [Methods] We investigated the microbial community structure by sequencing the V3?V4 hypervariable regions of bacterial 16S rRNA gene using the Illumina HiSeq 2500. Bacterial community composition, spatial distribution characteristics and environmental factors were combined and analyzed in an attempt to understand the key interactions. [Results] The 16S rRNA gene clone library analysis indicated that the most common phyla that were widely distributed in the 21 sites were: Proteobacteria (56.8%), Acidobacteria (8.9%), Chloroflexi (8.1%), Bacteroidetes (6.2%). Moreover, γ- Proteobacteria and δ- Proteobacteria were the most dominant classes in Proteobacteria. Total organic carbon and total organic nitrogen content in the near shore sediments is high due to the input of anthropogenic materia and gradually decreased offshore. The most significant influence on species composition and community structure within the study area were found to be from particle size (content<4 μm) and organic nitrogen load. [Conclusion] The microbial diversity in the inlet of Bohai Bay is very high and is significantly related to a variety of environmental parameters. Human activities play an important role in structuring the microbial diversity, community structure and distribution.

Key words:Bohai Bay, Sediment, Microbial community, 16S rRNA gene diversity