Bioreduction potential of chromate resistant bacteria isolated from chromite mine water of Sukinda, Odisha

Chromite mine water with a high concentration of Cr(VI) harbors highly chromium resistant bacteria, which could benefit the mine environment and be used for economic bioremediation strategy for chromate polluted ecosystems. In the present investigation, eight comparatively high chromium tolerant (>= 500 mg L-1) bacteria were isolated from water samples of the Sukinda chromite mine environment. Their morpho-biochemical and molecular (16S rRNA gene sequencing) characterization revealed that most of the bacteria belong to the members of the genus Bacillus, Lysinibacillus boronitolerens, and Alcaligenes faecalis. It was observed that all the eight bacterial isolates could reduce above 90% of Cr(VI) (p < 0.05) within 288 h. Out of these eight isolates, Alcaligenes faecalis (CWB-4) could able to reduce the maximum (99.77%) supplied Cr(VI) after 144 h, as the most efficient Cr (VI) reducing strain whereas, Licinibacillus boronitolerens (CWB-2) showed the least Cr(VI) reduction ability. The enzyme activities of the eight isolates were in the range of 0.67 to 5.07 U mL(-1). Hence, the high chromate tolerant bacterial isolates, with Cr (VI) reducing potential isolated in the present study, could be considered promising biological agents for bioremediation of environments polluted with chromium.