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The previously described chromium resistant bacterium, Enterobacter cloacae B2-DHA, was isolated from leather manufacturing tannery landfill in Bangladesh. Here we report the entire genome sequence of this bacterium containing chromium and other heavy metal resistance genes. The genome size and the number of genes, determined by massive parallel sequencing and comparative analysis with other known Enterobacter genomes, are predicted to be 4.22 Mb and 3958, respectively. Nearly 160 of these genes were found to be involved in binding, transport, and catabolism of ions as well as efflux of inorganic and organic compounds. Specifically, the presence of two chromium resistance genes, chrR and chrA was verified by polymerase chain reaction. The outcome of this research highlights the significance of this bacterium in bioremediation of chromium and other toxic metals from the contaminated sources.

This study is a part of our long term project on bioremediation of toxic metals and other pollutants for protection of human health and the environment from severe contamination. The information and results presented in this data article are based on both in vitro and in silico experiments. In vitro experiments were used to investigate the presence of arsenic responsive genes in a bacterial strain B1-CDA that is highly resistant to arsenics. However, in silico studies were used to annotate the function of the metal responsive genes. By using this combined study consisting of in vitro and in silico experiments we have identified and characterized specific genes from B1-CDA that can be used as a potential tool for removal of arsenics as well as other heavy metals from the contaminated environment., CC BY 4.0

Chromium and chromium containing compounds are discharged into the nature as waste from anthropogenic activities, such as industries, agriculture, forest farming, mining and metallurgy. Continued disposal of these compounds to the environment leads to development of various lethal diseases in both humans and animals. In this paper, we report a soil borne bacterium, B2-DHA that can be used as a vehicle to effectively remove chromium from the contaminated sources. B2-DHA is resistant to chromium with a MIC value of 1000 µg/mL potassium chromate. The bacterium has been identified as a Gram negative, Enterobacter cloacae based on biochemical characteristics and 16S rRNA gene analysis. TOF-SIMS and ICP-MS analyses confirmed intracellular accumulation of chromium and thus its removal from the contaminated liquid medium. Chromium accumulation in cells was 320 µg/g of cells dry biomass after 120 h exposure and thus it reduced the chromium concentration in the liquid medium by as much as 81%. Environmental scanning electron micrograph revealed the effect of metals on cellular morphology of the isolates. Altogether, our results indicate that B2-DHA has the potential to reduce chromium significantly to safe levels from the contaminated environments and suggest the potential use of this bacterium in reducing human exposure to chromium, hence avoiding poisoning.