Chlorobenzene degradation by Bacillus sp. TAS6CB: a potential candidate to remediate chlorinated hydrocarbon contaminated sites.

Chlorobenzenes (CB) are very commonly detected in ecosystems notably in the atmosphere, freshwater, sediments, and in urban sewage. They may contaminate ecosystems via the direct discharge of solid and liquid waste or through atmospheric volatilization. In the present study, CB degrading organisms were isolated from contaminated sites and screened for their effectiveness to degrade it. Isolates 6CB efficiently degrade CB. Isolate was identified by 16SrDNA and identified as Bacillus sp. TAS6CB. The cells showed positive chemotaxis towards CB, catechol, and salicylic acid indicates their potential for degradation of xenobiotic compounds. Degradation commence with production of chlorobenzene dioxygenase and further conversion into chlorocatechol, a central intermediate of chlorinated aromatic metabolism. Degradation rates were further enhanced by biosurfactant production as detected and confirmed by TLC analysis. Intermediate metabolites chlorocatechol and cis,cis-muconic acid, produced during the CB degradation were confirmed by UV scanning, HPLC and GC-MS analysis. Phytotoxicity study showed 40% of phytotoxicity decreased after 48 h of incubation by isolate. Thus, isolate can be used to remediate CB contaminated sites effectively.