ERP008968 PRJEB7956 ena-STUDY-SYSU-09-12-2014-16:15:10:443-111 Microbial Community in High Arsenic Shallow Aquifers in Hetao Basin of Inner Mongolia, China by 454 Pyrosequencing A comprehensive survey of microbial community with 454 Pyrosequencing was carried out in 20 groundwater samples (4 low and 16 high arsenic groundwater) and 19 sediments from three boreholes (two high arsenic boreholes and one low arsenic borehole) in a high arsenic groundwater system located in Hetao Basin, Inner Mongolia by. A total of 233,704 reads and 12-267 species-level OTUs were detected. Richness and diversity of microbial communities in high arsenic sediments are higher than those in high arsenic groundwater. Microbial community structure was significantly different either between low arsenic and high arsenic samples or between groundwater and sediments. Acinetobacter, Pseudomonas, Psychrobacter and Alishewanella were the top four predominant populations in high arsenic groundwater, while Thiobacillus, Pseudomonas, Hydrogenophaga, Enterobacteriaceae, Sulfuricurvum and Arthrobacter were distinctly dominated in high arsenic sediments. Acinetobacter was distinctly dominated in groundwater with the markedly high relative abundance (average 62.41%), and Thiobacillus was significantly abundant (average abundance 24.62%) in sediments. Archaeal sequences of high arsenic groundwater were mostly related to methanogens. Groundwater and sediment samples were divided into low and high arsenic groups based on geochemical parameters and microbial communities by hierarchical clustering and PCoA analyses. This suggested that arsenic is a critical environmental factor that contributes to the difference microbial community structure. BIO-ENV and co-inertia analyses showed that some other geochemical parameters including TOC, SO42-, SO42-/TS and Fe2+ were also the important factors causing the difference of the microbial community. The results of this study expand our current understanding of microbial ecology in high arsenic aquifers and emphasize the potential importance of microbes in arsenic mobilization in the shallow aquifers of Hetao Basin, Inner Mongolia. A comprehensive survey of microbial community with 454 Pyrosequencing was carried out in 20 groundwater samples (4 low and 16 high arsenic groundwater) and 19 sediments from three boreholes (two high arsenic boreholes and one low arsenic borehole) in a high arsenic groundwater system located in Hetao Basin, Inner Mongolia by. A total of 233,704 reads and 12-267 species-level OTUs were detected. Richness and diversity of microbial communities in high arsenic sediments are higher than those in high arsenic groundwater. Microbial community structure was significantly different either between low arsenic and high arsenic samples or between groundwater and sediments. Acinetobacter, Pseudomonas, Psychrobacter and Alishewanella were the top four predominant populations in high arsenic groundwater, while Thiobacillus, Pseudomonas, Hydrogenophaga, Enterobacteriaceae, Sulfuricurvum and Arthrobacter were distinctly dominated in high arsenic sediments. Acinetobacter was distinctly dominated in groundwater with the markedly high relative abundance (average 62.41%), and Thiobacillus was significantly abundant (average abundance 24.62%) in sediments. Archaeal sequences of high arsenic groundwater were mostly related to methanogens. Groundwater and sediment samples were divided into low and high arsenic groups based on geochemical parameters and microbial communities by hierarchical clustering and PCoA analyses. This suggested that arsenic is a critical environmental factor that contributes to the difference microbial community structure. BIO-ENV and co-inertia analyses showed that some other geochemical parameters including TOC, SO42-, SO42-/TS and Fe2+ were also the important factors causing the difference of the microbial community. The results of this study expand our current understanding of microbial ecology in high arsenic aquifers and emphasize the potential importance of microbes in arsenic mobilization in the shallow aquifers of Hetao Basin, Inner Mongolia.