Molecular Characterization of the Total Bacteria and Dissimilatory Arsenate-Reducing Bacteria in Core Sediments of the Jianghan Plain, Central China

Abstract

ABSTRACTArsenic contamination in groundwater has been reported in the Jianghan Plain of China since 2005, yet little is known about the microbial communities involved in As mobilization in this area, especially the dissimilatory arsenate-reducing bacteria (DARB) communities. Here, we conducted a cultivation-independent investigation on core sediments collected from a region with arsenic-contaminated groundwater in the Jianghan Plain to reveal the total bacteria and DARB community structures. Highly diverse As-resistant bacteria communities were found from sediment samples via high-throughput sequencing of 16S rRNA genes. Notably, we identified 27 unique arrA gene (encoding the alpha subunit of dissimilatory arsenate reductase) phylotypes, none of which was related to any previously described arrA gene sequence. This suggests a novel and unique DARB community in the sediments of the Jianghan Plain and expands our knowledge about the distribution and diversity of this group of bacteria in natural environments. Moreover, RDA and CCA demonstrated that total bacterial communities and specific functional groups are controlled by different environmental factors. Specifically, sediment pH, NH4+, total nitrogen, total Fe, total organic carbon and total phosphorus were the key factors driving total bacterial community compositions, while As significantly shaped DARB community structures. This report is the first to describe DARB communities and their correlation with environmental factors in Jianghan Plain sediments, which could give us clues about the origin of the arsenic contamination of groundwater in this region.