Characterization of multiple metal resistant Bacillus licheniformis and its potential use in arsenic contaminated industrial wastewater

In the present study, the arsenic bioremediation ability of Bacillus licheniformis (dubbed as A6) was determined. The strain was isolated from metal polluted wastewater and was identified on the basis of 16S rRNA sequence homology with accession number of KX 785,171. The bacterium showed resistance against multiple toxic heavy metals, and MIC against arsenic was 3000 µg/ml. Resistance of the bacterium against other toxic metal ions was 3000 µg/ml (Cr), 50 µg/ml (Hg), 1000 µg/ml (Mn), 4000 µg/ml (Se), 500 µg/ml (Pb), 100 µg/ml (Co), 70 µg/ml (Cd) and 100 µg/ml (Zn). The optimum growth temperature was 37 °C while pH was 7. The strain also showed resistance against commonly used antibiotics except ceftriaxone 30 µg and amoxicillin with clavulanic acid (2:1) 3 µg. B. licheniformis could oxidize arsenite into arsenate 86 and 98% after 48 and 96 h from the medium at optimum growth conditions. Due to its high oxidation potential, B. licheniformis can be used in the biological treatment of wastewater containing arsenic.