EFFECT OF URBAN WATER POLLUTION ON THE HOMOGENEITY OF MICROBIAL COMMUNITY IN SEDIMENTS
As an urban river,the Jinan section of the Xiaoqing River has not only a source clean segment,but also a section for collecting urban and domestic waste water,making it a natural model for studying urban river pollution due to its basin and pollution characteristics.The study of sediment microbial community in Xiaoqing River is of fundamental significance for understanding the current situation of sediment microorganisms,and it can also provide a reference for the study of microbial community in typical urban polluted rivers.This study used high-throughput sequencing technology of 16S rRNA to analyze microbial diversity and community structure in sediment samples from different sections.The results showed that the level of microbial diversity in Xiaoqing River sediment samples was relatively high,but the microbial community composition varied at different sections(R2=0.73,P=0.0010),with difference of the distinct species at each section.The microbial community composition in sediment of urban sections tended to be homogeneous,while those at the source and upstream sections are similar but less homogenized than those in the urban sections,indicating that the urban environment had a significant natural selection effect on sediment microbial community of the river,and reduced sediment microbial diversity.Further analysis using LEfSe revealed that there were 48 taxa showing significant differences among the six sections(LDA>4),Among them,the class Firmicutes(LDA=4.69)contributed the most to differences among all groups,and was significantly enriched in urban sections,This indicates that the environmental factors in urban sections had a strong directional selection effect on sediment microbial community,leading to a trend of homogenization in microbial composition and a subsequent decrease in microbial diversity.This study revealed that the selection effect of urban environment not only significantly reduced the α diversity level of sediment microbial in urban sections,but also significantly reduced the β diversity level,leading to an increase in homogeneity of microbial communities in urban sections.