长江三峡上游水域细菌群落结构与功能预测

Community structure and function predication of bacterial communities in the upper reaches of the Three Gorges of the Yangtze River

摘要:

【目的】揭示三峡附近支流和长江干流细菌群落组成,共现网络特征和对网络有重要作用的中心节点微生物,进一步研究三峡上游水域细菌群落的代谢功能。【方法】本研究于长江北岸四条一级支流和附近干流(香溪河、大宁河、朱衣河、梅溪河、长江干流)采集水样,基于16S rRNA基因Pacbio测序技术和生物信息学方法分析细菌群落结构,Tax4Fun功能预测分析细菌群落的代谢功能。【结果】(1)长江三峡上游水域主要优势菌门为变形菌门(Proteobacteria,66.4%)、拟杆菌门(Bacteroidetes,13.2%)和蓝细菌门(Cyanobacteria,6.2%)。变形菌门中,γ-变形菌最为丰富,其次是α-变形菌。多样性指数和丰富度指数表明研究区域微生物种类较为丰富。(2)共现网络分析结果表明,长江三峡上游附近水域网络具有"小世界"特征,鞘脂单胞菌科(Sphingomonadaceae)、绿弯菌门(Chloroflexi)、出芽菌科(Gemmataceae)、弯曲杆菌(Flectobacillus)和蟑螂杆状体科(Cryomorphaceae)是对共现网络结构有重要作用的中心节点微生物,在群落结构和多样组成中扮演着重要角色。(3) Tax4Fun功能预测共发现6个一级功能和42个二级功能,长江三峡上游水域细菌群落代谢比较活跃。【结论】长江三峡上游水域细菌群落多样性高,中心节点微生物多为稀有微生物,稀有微生物在维持群落结构中发挥重要作用。细菌群落代谢功能分析表明,长江三峡上游水域细菌群落代谢途径丰富,有益于水域的水体健康。了解微生物群落的分布和相互作用特征,将为长江生态系统的健康发展、水资源的利用和水环境的改善提供基础数据和科学依据。

Abstract:

[Objective] This paper aims to reveal the bacterial community structure in the Three Gorges of the Yangtze River,the topological properties of co-occurrence network and its hub microorganisms,and the metabolic functions of the bacterial community.[Methods] Water samples were collected from the mainstream and four tributaries (Xiangxi River,Daning River,Zhuyi River,and Meixi River) of the Yangtze River.PacBio 16S rRNA high-throughput sequencing and bioinformatics analysis were performed to elucidate the bacterial community structure and Tax4Fun was employed to predict the metabolic functions of the community.[Results] (1) The dominant phyla in the upper reaches of the Three Gorges of the Yangtze River were Proteobacteria(66.4%),Bacteroidetes(13.2%),and Cyanobacteria(6.2%).In Proteobacteria,Gammaproteobacteria was most abundant and followed by Alphaproteobacteria.The diversity index and richness index implied the rich microbial species in the study area.(2) Co-occurrence network formed a "small world" topology,and Sphingomonadaceae,Chloroflexi,Gemmataceae,Flectobacillus,and Cryomorphaceae were the central microorganisms which played a crucial part in maintaining the community structure and diversity.(3) A total of 6 functions in level 1 and 42 functions in level 2,which mainly involved in metabolism and genetic information processing,were found in Tax4Fun function prediction,suggesting the active metabolism of the bacterial community.[Conclusion] Bacterial community in the upper reaches of the Three Gorges was of high diversity,and the hub microorganisms were mainly rare microorganisms which played an important role in maintaining the community structure.The bacterial community in the upper reaches of the Three Gorges featured abundant metabolic pathways,which was beneficial to the health of the water body.Clarifying the distribution and interaction characteristics of microbial community could lay a scientific basis for the healthy ecosystem development,water resource utilization,and water environment improvement of the Yangtze River.