Study On Bacterial Community Structure And Methane-oxidizing Bacteria In The Main Section Of The Yangtze River In Chongqing

In this study,the main stream of the Yangtze River and its tributaries in the main urban section of Chongqing were selected as the research area,Lijiatuo,Daxigou,Cuntan,Tangjiatuo,and Guojiatuo were selected as sampling points.Used high-throughput sequencing and other molecular biology methods and multivariate statistical analysis methods to study the bacterial community structure and methanotrophic bacteria in the sampling area,analyze the temporal and spatial differences of bacteria and methanotrophs in urban rivers,explore the correlation between bacteria,methanotrophs and environmental factors,and study the response relationship between methanotrophs and methane and carbon dioxide respectively.The conclusions of the study are as follows:（1）There are temporal and spatial differences in the bacterial diversity of the Yangtze River in the main urban section of Chongqing.The spatial differences are reflected in the bacterial diversity of sediments higher than that of water bodies,the bacterial diversity of mainstream water bodies is higher than that of tributary water bodies,and the downstream points closer to the sewage treatment plant The bacterial diversity is the highest;the time difference is reflected in the bacterial diversity in summer than in autumn and winter.The bacterial community is mainly composed of Proteobacteria,Actinobacteria,Bacteroides,Verrucomicrobia,Planktomycetes,Cyanobacteria,Acidobacteria,Firmicutes,etc.The relative abundance of some of the bacteria phyla exists in time and space.The difference in space is that the relative abundance of the Bacteroides phylum is higher than the sediment in the water body,higher than the tributary in the main stream,while the Chloroflexi phylum is higher than the water in the sediment,and the Cyanobacteria is higher than the main stream in the tributary;the time difference shows that the relative abundance of Bacteroides in winter is relatively high,the relative abundance of Saccharibacteria and Acidobacteria in autumn is relatively high,and the relative abundance of most of the phylums such as Verrucomicrobia and Planktomycetes is relatively high in summer.NH₄⁺-N,NO₃^--N,CO₂,DO,T and TOC have a greater impact on the bacterial communities in the main Chongqing section of the Yangtze River,only TOC in the mud is negatively correlated with Proteobacteria.（2）The distribution of methane concentration in the main city section of the Yangtze River in Chongqing has temporal and spatial changes.The methane concentration in the lower reaches of the main city section of the Yangtze River is higher than that in the middle and upper reaches,and the bottom water is higher than the surface water;the methane concentration is highest in September in autumn,followed by June in summer and January in winter.The diversity of MOB bacterial communities in the Yangtze River in the main city section of Chongqing also has temporal and spatial differences.The spatial differences are manifested in that the community diversity is higher in the sediments than in the water body,the main stream is higher than the tributary,and the main stream is higher than the upstream and downstream points.,The upstream point of the sewage treatment plant is higher than the downstream point of the sewage treatment plant;the time difference is that the diversity of the MOB bacterial community in summer is higher than that in autumn and winter.The MOB community is dominated by Methylcystis TypeⅡas the dominant species.The environmental factors that mainly affect the structure of the MOB bacterial community in the main urban section of the Yangtze River in Chongqing are NH₄⁺-N,DO,T and p H.CH₄ and CO₂ are significantly correlated with MOB bacterial communities.CO₂ is positively correlated with unclassified＿c＿Gammaproteobacteria,and CH₄ is negatively correlated with norank＿c＿environmental＿samples＿p＿Proteobacteria.（3）There are temporal differences in the diversity of DAMO bacteria in the Yangtze River in the main urban section of Chongqing.The community diversity is higher in summer than in autumn and winter,and the community abundance is higher in winter than in summer and autumn.The majority of DAMO bacterial communities belong to the NC10 phylum.Among them,OTU7,which is highly homologous to DAMO bacteria in the sediments of the North Canal,is the dominant bacterial species in the main section of Chongqing of the Yangtze River.Some DAMO bacteria have temporal and spatial differences.The environmental factors that mainly affect the community structure of denitrifying anaerobic methane oxidizing bacteria in the main section of the Yangtze River in Chongqing are DO,NO₃^--N,p H and NH₄⁺-N.The DAMO bacterial community structure is significantly correlated with CO2.The DAMO bacterial diversity is significantly correlated with CH₄ and CO₂.As the concentration of CH₄ decreases and the concentration of CO₂ increases,the community diversity of DAMO bacteria also increases,and the abundance of the community decreases accordingly.