Relationships between Microbial Compositions and Hydrochemical Factors in Nitrate Contaminated Groundwater of Hun River Alluvial Proluvial Fan, China

The objective of this study was to explore the microbial community diversities and the relationships between microbial community compositions and hydrochemical factors in nitrate contaminated groundwater of Hun River alluvial plain. The method of polymerase chain reaction (PCR)-denaturing, gradient gel electrophoresis (DGGE) gene fingerprints combined with canonical correspondence analysis（CCA） were applied. The Operational Taxonomic Units (OTUs) of all the sampling sites had a certain degree of heteroplasmy and ۷۵% OTUs presented in less than half of the sampling sites. The un-weighted pair group mean average (UPGMA) cluster analysis showed that the microbial community similarity of all the sampling sites were not relatively high (۰.۶-۰.۸). The distribution of microbial community positively correlated with nitrate. The dominant bacteria of the nitrate contaminated groundwater mainly included Hyphomicrobium denitrifican sp., Halanaerobium praevalens sp., Desulfotomaculum reducens sp., Nitrosospira multiformis sp., among which the Nitrosospira multiformis sp.and Sulfurovum sp. existed in all the sampling sites. CCA results indicated that Mn۲+and NO۳- were the most relevant hydrochemical factors to regulate the microbial composition in nitrate contaminated groundwater of this area, and next were Fe۲+ and SO۴۲- . The results could provide references for the bioremediation of the nitrate contaminated groundwater of Hun River alluvial plain