Study On The Characteristics Of Water Microbial Community In Lake-River Ecotone Of Poyang Lake

The effect of water environment in Poyang Lake is profound and lasting around the world,so it is particularly important to maintain the balance of the ecological system in Poyang Lake.Microorganism is the main driver of the material circulation in the water ecosystem,which affects and regulates the environmental quality of the water body.As an important pollution area and buffer zone,Lake-River Ecotone of Poyang Lake has more abundant microbial diversity.In this study,we studied the physicochemical properties,microbial diversity index and bacterial community composition of surface water bodies in the Lake-River Ecotone of the Poyang Lake during the wet season and dry season,The conclusion is as follows:(1)The physical and chemical properties of the surface water in the Lake-River Ecotone of the Poyang Lake existed some spatial differences and time differences during the wet season and dry season,and the time differentiation was greater than the spatial differentiation on the whole.The content of total nitrogen and total phosphorus in the region with frequent human activities was high,it shows that human activities have a more obvious effect on the water quality of the surface water body of the LakeRiver Ecotone of the Poyang Lake.(2)Eleven samples collected from September were subjected to high throughput sequencing to obtain 333,794 effective base sequences,and 5,796 OTUs were obtained,and it was found that all the bacteria in the samples were 34 phylum,74 class,154 order,254 family,414 genus and 678 species.Thirteen samples collected from December were subjected to high throughput sequencing to obtain 469,181 effective base sequences,and 9,959 OTUs were obtained,and it was found that all the bacteria in the samples were 44 phylum,101 class,193 order,348 family,652 genus and 1,107 species.(3)Proteobacteria was the dominant species of phylum in the wet and dry season of the Lake-River Ecotone of the Poyang Lake,which accords with the basic characteristics of microbial composition in typical freshwater bodies.Actinobacteria and betaproteobacteria were the dominant groups in the class classification,and its spatial distribution differentiation was more obvious in the temporal change.The hgc I_clade under the actinobacteria was the dominant groups in the species classification,but its proportion is obviously reduced in the dry period.(4)Redundancy analysis of environmental factors and microbial community structure revealed that the explaining variable between the dominant bacteria and environmental factors were better,and it existed the corresponding positive correlation and negative correlation.This illustrated that there was a certain correlation between the physical and chemical indexes of the surface water body of the Lake-River Ecotone of the Poyang Lake and the spatial and temporal distribution of microbial community structure.(5)There was a close relationship between the microbial community structure of different sample points of the Lake-River Ecotone of the Poyang Lake,but individual sample points are still expressed the significant differences in space distribution,and the spatial difference in dry season is obviously greater than that in wet season.