Study of mercury resistance and Fourier transform infrared spectroscopy‐based metabolic profiling of a potent Bacillus tropicus strain from forest soil

Abstract

Mercury (Hg) is a highly toxic heavy metal and Hg‐resistant indigenous bacterial isolates may offer a green and cost‐effective bioremediation strategy to counter Hg contamination. In this study, a potent Hg‐resistant bacterium was isolated from the forest soil of a bird sanctuary. Identification using matrix‐assisted laser desorption ionization‐time of flight mass spectrometry depicted the isolate as a strain of Bacillus tropicus, validated by morphological, biochemical, and molecular studies. The isolate demonstrated biological Hg removal efficiency and capacity of 50.67% and 19.76 mg g−1, respectively. The plasmid borne resistance determinant, merA, encoding mercuric reductase, was detected in the bacterium endowing it with effective Hg volatilization and resistance capability. A Fourier‐transform infrared spectroscopic comparative metabolic profiling revealed the involvement of various functional groups like –COOH, ‐CH2, ‐OH, PO4− and so on, resulting in differential spectral patterns of the bacterium both in control and Hg‐exposed situations. A temporal variance in metabolic signature was also observed during the early and mid‐log phase of growth in the presence of Hg. The bacterium described in this study is the first indigenous Hg‐resistant strain isolated from the Uttar Dinajpur region, which could be further explored and exploited as a potent bioresource for Hg remediation.