Biotransformation and bioaccumulation of arsenic by Brevibacillus brevis isolated from arsenic contaminated region of West Bengal

Microorganisms influence the fate of metals in environment. Increasing anthropogenic and geogenic activity had increase the risk of arsenic pollution and this has forced the future research area to involve microbes-metal toxicity to achieve bioremediation. The present study deals with the role of arsenite transforming bacteria and incorporates them into remediation design. Sample was collected from Haringhata in Nadia district which is a known arsenic contaminated zone. Out of six isolated bacteria one bacterium revealed as arsenic tolerant bacteria which shows molecular similarity with Brevibacillus brevis from 16s rRNA studies. It can tolerate upto 1000 mg/L of arsenite and 500 mg/L of arsenate. Both the arsenic species has toxic effects on its protein concentration. The strains can tolerate upto a certain limit after that their growth ceased. This strain can accumulate and also transform arsenite to arsenate. The transformation capacity of strain was assessed qualitatively and quantitatively. The strain can transform 90% of arsenite to arsenate. But the transformation capacity only reveals as detoxification mechanism and has no relation with their respiration. Morphological biochemical and molecular identification was done. As arsenate is absorbed into iron oxyhydroxides and get immobilize thus a remediation mechanism can be designed with this strain.