Diversity and arsenic-tolerance potential of bacterial communities from soil and sediments along a gold tailing contamination gradient.

Gold tailings often release arsenic (As) contaminants into the surrounding environment. Microorganisms play an important role in the As cycle, whereas the effects of As on bacterial communities remain unclear. To reveal the effects of As on the diversity of bacterial communities and their As-tolerance potential, farmland soil and river sediment samples were collected at various distances from tailings in the Dandong area of northeastern China. The bacterial communities were analyzed using high-throughput sequencing of 16S rRNA genes. The membrane transport proteins ArsB and (or) ACR3 pump As(III) out of the cell to resist As toxicity. We studied the abundance and phylogeny of ArsB and ACR3 using PCR-based clone libraries and quantitative PCR. The bacterial community was divided into 10 phyla and 59 genera. The transformation from As(V) to As(III) was predominant, which was coupled with denitrification. Both ArsB and ACR3 likely evolved from different orders of Proteobacteria. The arsB gene seems to be more stable in bestowing bacteria with the capability to respond to the As concentration. Moreover, As with iron, manganese, and total organic carbon also influenced the clustering relationships of samples and bacterial distribution.