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.