Identification of Bacterial Community and Arsenate-Reducing Bacteria Associated with a Soda Lake in Khovsgol, Mongolia

Soda lakes are extreme habitats characterized by high pH, high salt content, and occasionally associated with elevated concentrations of trace elements from volcanic origins, including arsenic (As). We characterized the bacterial community associated with a soda lake in Khovsgol, Mongolia by using both cultivation-independent and -dependent methods. Geochemical analysis of the salt evaporites present in lakeshore soils showed elevated concentrations of As, Se, and nitrate with high pH values (>8.5). Bacterial populations present in the same samples were investigated using 16S rRNA gene sequence analysis. The majority of bacterial 16S rRNA gene sequences recovered from the soda lake samples were affiliated with haloalkaliphiles in phyla Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. Enrichment cultures exhibiting arsenate and selenate reductions were obtained. The results provide evidence that indigenous microorganisms associated with soda lake environments are capable of As and Se transformation and may contribute to the speciation and mobility of As and Se in situ.