Study On The Characteristics Of Microbial Community And Response Of Environmental Factors In Bahe River(Chanba Eco-Region)

Due to the expansion of cities and the continuous settlement of population,the quality of river water environment is declining,which leads to great changes in the river ecological environment.With the establishment of Chanba eco-region,a national eco-region,more and more attention has been paid to the environmental management and pollution control of rivers.As an important participant of material circulation and energy exchange in aquatic ecosystem,microorganisms have unique and irreplaceable roles.Therefore,it is of great significance to study the microbial community structure of Chanba River and analyze the water ecological situation for the ecological restoration and environmental governance of the river.The main research contents and results are as follows(1)The surface water,sediment and emergent plant rhizosphere soil samples were collected from the lower reaches of the Chanba River in Xi'an.T he surface water quality was determined by field measurement and indoor experiment.According to the results of water quality,the spatial distribution characteristics and water quality change trend of water quality indexes at the outlet of sewage treatment plant were revealed by single factor evaluation,set pair analysis and principal component analysis.Comparing the two evaluation methods,the results show that the set pair analysis method can determine the water quality standard more objectively.(2)Based on high-throughput sequencing method,a total of 47 phyla,118 classes,296 orders,518 families and 1051 genera of water samples,50 phyla,134 classes,301 orders,508 families and 1009 genera of sediment samples and 41 phyla,110 classes,247 orders,388 families and 708 genera of soil samples were detected.The distribution characteristics of microbial communities in water,sediment and rhizosphere soil of emergent plants were studied qualitatively.The results showed that there were common dominant species at the level of microbial phylum in this area,and there were significant differences in community structure at the level of class and genus.(3)The community abundance and diversity of the three samples were analyzed by calculating the alpha diversity index of microbial community.The similarity and diversity of microbial community were further studied by cluster analysis,PCA and LEfSe analysis.The results showed that the abundance and diversity of microbial community had obvious spatial distribution characteristics;the samples were clustered preferentially when the types were the same or similar,and the sampling locations were the same or similar;there were 16 different genera at the level of water,and 12 different genera at the level of sediment.(4)Based on RDA,the correlation between water environmental factors and microbial community structure was explored.Through Pearson correlation analysis of SPSS software,the response relationship between the diversity and composition of microbial community and en vironmental factors was analyzed.RDA showed that only pH(P=0.0372)of the eight environmental factors reached significant level.(5)By analyzing the association network of more than 100 kinds in 10 samples,we can observe the relationship between different sample types and species.Among them,the distribution of correlation network of water samples is relatively concentrated,and the distribution of sediment and soil samples in the correlation network is relatively scattered.At the same time,there is a close relationship between the genera of bacteria in sediment and soil samples,and the main genera of bacteria in the two types of samples are highly coincident.According to the functional metabolism analysis of PICRUSt2,the primary metabolic pathway is mainly biosynthesis.In the biosynthetic pathway:amino acid synthesis,carbohydrate synthesis,fatty acid synthesis are the main secondary metabolic pathways.