Characterization of Microbial Community Structure Associated with Pollution in Xiaoqing River Sediment

Jialin Li, Tao Zou, Shuxian Yu, Song Qin

To understand the impacts of anthropogenic activities on structure and composition of microbial communities and evaluate how microbial communities respond environmental gradients at river sediments, the composition of microbial communities in sediments from Xiaoqing River (in spring, summer and autumn) were assessed using DGGE and real-time PCR approaches. Meanwhile, 16S rRNA clone library construction of three sites was constructed to represent the composition and structure of microbial communities in the three distinct site-groups. The gene copy number was ranged from 107-108 cells/g that was most influenced by sample sediment density and medium grain size. Through analysis of DGGE gel profile, there were no distinct variation on richness, evenness and Shannon-Weaver index with all samples, which ranged 3.69-5.21, 1.73-2.30, and 0.56-0.76 respectively. The clustering result on the DGGE patterns showed that the microbial diversity of all samples were more similar than 40%, while the distinction was formed with three groups at a level of  46% similarity. Redundancy analysis revealed that the distribution of microbial composition seemed to be determined by the variables of nitrite, medium grain size and total carbon content. The clone library of three sites revealed that the Proteobacteria was the dominant phylum, which consistent with DGGE bands sequencing result. In addition, members of Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Verrucomicrobia were recorded in all three libraries. The distribution of functional populations as denitrifier and anammox bacteria will be the focus of future research.