龙江沉积物细菌群落及其对环境差异响应分析

Analysis of Bacterial Community in Sediments of Longjiang River and Its Response to Environmental Changes

2012年广西龙江“镉污染”事件经化学沉淀法处理后,该区域的重金属污染情况一直备受关注。为了解龙江河沉积物中重金属对细菌群落分布特征的影响,以龙江河宜州区河段从上游拉浪到下游三岔5个采样点(LA、HY、GW、XJ、SC)的沉积物为研究对象,通过Illumina高通量测序技术,分析沉积物中细菌群落结构和多样性,并结合环境因子分析微生物的响应特征。结果表明,研究区域的优势细菌类群包括变形菌门(43.87%)、绿弯菌门(15.55%)、酸杆菌门(15.50%)、放线菌门(14.11%)等。其中γ-变形菌纲、α-变形菌纲、δ-变形菌纲、厌氧绳菌纲为纲水平的优势类群。由于工业环境的影响,中游GW样区的细菌多样性和丰富度明显低于其他样区,而理化指标明显高于其他样区,龙江河沉积物细菌群落在空间上存在一定的差异性。营养物质(TN、TP、AP)和重金属(Cu、Ni、As)是沉积物细菌群落结构的主要影响因子,其中Cu、Ni、As与变形菌门呈显著负相关(P<0.05),与绿弯菌门呈显著正相关(P<0.05)。沉积物重金属对细菌多样性和群落结构产生显著影响,重金属敏感菌群可作为指示菌反映河段的环境状况,为后期重金属耐受菌群开发奠定了理论基础。

Heavy metal pollution in the Longjiang River has drawn public concerns since the"cadmium pollution"incident of the River occured in 2012,which although was treated later by using the chemical precipitation method.To make certain the effects of heavy metal in the River's sediments on the distribution characteristics of bacterial communities,investigations were carried out,which involved top sediments sampled from five sampling sites(LA,HY,GW,XJ,SC)in the Yizhou reaches of the Longjiang River,and high-throughout Mi-seq sequencing technology being used to analyze bacterial communities and bio-diversity in the sediments,as well as their responses to environmental factors.The investigations concluded that the dominant phyla in the sediments distributed in the study area comprised Proteobacteria(43.87%),Chloroflexi(15.55%),Acidobacteria(15.50%),and Actinobacteria(14.11%);and-Proteobacteria,α-Proteobacteria,8-Proteobacteria and Anaerobionae were the dominant classes.As for the influences of industrial environment,it was found the bio-diversity and abundance of bacteria at GW sampling site(within the River's mid-reach)were obviously lower than other areas of sampling sites,but the physical and chemical indexes were remarkably high.The cluster analysis showed that there were certain differences of the bacterial community in the River's sediments;and the redundancy analysis(RDA)indicated that nutrient parameters(TN,TP,AP)and heavy metals(Cu,Ni,As)affected the bacterial community structure,heavy metals(Cu,Ni,As)being negatively correlated with Proteobacteria,and positively correlated with Chloroflexi.In summary,the bacterial diversity and community structure in the sediments of the Longjiang River was significantly related to heavy metals,and the heavy-metal-sensitive bacteria can be used as an indicator to reflect the environmental status of the River reaches.The conclusions could laid a theoretical foundation for the screening of heavy-metal-tolerant-microorganism in later stage.