LAUSR

Abstract Arsenate reducing bacteria are known to potentially contribute to metabolize or transform arsenic from groundwater or sediments. Environmental arsenic bioavailability and the influence of these bacteria on arsenic mobilization have not been comprehensively investigated till date. In this present study, Bacillus sp. BAR1, isolated from the severely arsenic contaminated groundwater of Bhojpur, Bihar within the middle Indo – Gangetic plain were thoroughly characterized for its detailed physiological, biochemical and phylogenetic analysis. It was revealed to be a gram-positive heterotrophic bacteria, capable of utilizing arsenate as an electron acceptor under aerobic conditions. The strain showed a broad range of tolerance to several heavy metals and transition metal ions (Hg, Zn, Cr, Cu, Cd, Ni) including arsenic and utilized several carbon sources along with complex sugars. The growth of the isolate also substantially increased in the presence of arsenate, signifying the utilization of arsenate as an added energetic advantage during the detoxification mechanism of arsenate to arsenite. The arsenate reduction efficiency was optimized to 72% at a temperature of 30 °C, inoculum 2%, an initial As (V) concentration of 100 mM at 20 h using response surface methodology. The results shed light on the key role of Bacillus sp. BAR1 in the self-purification of heavy metal-laden waters and in the arsenic biogeochemical cycle.