Reduction of Cr(VI) by Bacillus species isolated from tannery effluent contaminated sites of Tamil Nadu, India

Hexavalent chromium [Cr(VI)] is a heavy metal pollutant in the environment released through leather tanning. In this context, the present study was envisaged to isolate and identify chromium reducing bacteria in order to employ them towards detoxification of chromium. In general, bacteria are ecofriendly and cost-effective which can be efficiently used in bioremediation processes. The collected tannery effluents yielded considerable Bacillus species. These isolates demonstrated well for their resistance which showed exceptional Cr(VI) reduction within 48 h under aerobic conditions. Mostly, chromium resistance confers through Chromate transporters which involves metabolic reduction of toxic Cr(VI) to non-toxic Cr(III). Distribution of chr genes in Bacillus species were identified from their genome through UniProt. Treatment of raw tannery effluent employing these isolates individually or as a consortia reduced Cr(VI) significantly. Thus, these bacterial strains, could evolve as a potential organisms to reduce toxic Cr(VI) to its non-toxic Cr(III) form in chromium contaminated sites.