Bioremediation Potential of Mercury by Bacillus Species Isolated from Marine Environment and Wastes of Steel Industry

ABSTRACT The marine environment is the most dynamic and most variable among the natural environments present on the globe due to its continuously changing patterns of salinity, sea surface temperature, pH, and pressure. Thus, bacteria inhabiting this environment possess the inbuilt mechanisms of adaptation necessary in such fluctuating environmental conditions, and the harboring of heavy metal–resistant genes adds to their efficiency with regard to metal remediation compared with their terrestrial counterparts. Two highly mercury-resistant isolates, one from the marine environment and another from steel industry waste, were identified as Bacillus thuringiensis PW-05 and Bacillus sp. SD-43, respectively, by 16S rRNA gene sequence analysis. When various characters of these two isolates, e.g., biochemical, morphological, antibiotic resistance, and tolerance to other heavy metals, were analyzed, they were found to share common features. However, the marine Bacillus isolate (PW-05) was found to be more capable than its terrestrial counterpart in terms of mercury volatilization capability, i.e., 94.72% in the case of PW-05 and 60.06% in the case of SD-43. Hence, marine bacteria can be used more efficiently than their terrestrial counterparts for enhanced bioremediation of mercury in contaminated envi-ronments.