Abstract: We analyzed the structure and function of microbial community and their relationships with environmental factors in aquaculture ponds of mitten crab and water of exogenous river, based on Illumina HiSeq highthroughput sequencing technique. A total of 541349 effective tags were obtained in six water samples of ponds, which were clustered into 2938 OTUs (operational taxonomic units). A total of 551891 effective tags were obtained in six water samples of exogenous river, which were clustered into 2779 OTUs. A total of 557736 effective tags were obtained in six sediment samples of ponds, which were clustered into 8920 OTU. The α-diversity (Sobs index, Shannon index, Simpson index, and Chao index) of the sediment samples was significantly higher than that of the water samples. The results of β-diversity analysis showed that the samples could be divided into two groups according to the microbial community structure, i.e., sediment group and water group. Proteobacteria, Actinobacteria, Cyanobacteria, Verrucomicrobia, Planctomycetes, and Bacteroidetes were the dominant phyla in waters of aquaculture ponds and exogenous river. Proteobacteria, Planctomycetes, Acidobacteria, Verrucomicrobia, Chloroflexi, and Bacteroidetes were the dominant phyla in the sediments. The results of redundancy analysis showed that temperature (r²=0.915, P<0.01), pH (r²=0.8,P<0.01), dissolved oxygen (r²=0.65, P<0.01), and total hardness of water (r²=0.756, P<0.01) were significantly correlated with bacterial community structure, while NH₃-N, NO₂^--N, COD, NO₃^--N, TP, and TN were not significantly correlated with bacterial community structure. The results of variance partitioning analysis showed that pH, temperature, and dissolved oxygen were highly contributed to the microbial community distribution at phylum level, with a contribution rate of 44.14%, 41.20%, and 33.2%, respectively. A total of 37 predicted functions were obtained at level 2 by TaxFun method. Carbohydrate metabolism and amino acid metabolism were the dominant functions in both water and sediment. The abundance of functional genes involved in amino acid metabolism, lipid metabolism, membrane transport, xenobiotic biodegradation and metabolism in the sediments was significantly lower than that in the water, while the abundance of functional genes involved in energy metabolism, glycan biosynthesis and metabolism in the sediments were significantly higher than that in the water. Our results provide a scientific basis for the environmental regulation and ecosystem maintenance of mitten crab culture.

Key words: Eriocheir sisensis, 16S rDNA, microbial community structure, environmental factor, Tax4Fun.