Blotransformation of chlorpyrifos and bioremediation of contaminated soil

Five aerobic consortia capable of degrading chlorpyrifos as a sole carbon source in aqueous medium showed degradation in the range of 46-72% after 20 days. Pseudomonas fluorescence, Brucella melitensis, Bacillus subtilis, Bacillus cereus. Klebsiella species, Serratia marcescens and Pseudomonas aeroginosa, isolated from these consortium, showed 75-87% degradation of chlorpyrifos as compared to 18% in control after 20 days of incubation. Bioremediation of chlorpyrifos-contaminated soil with P. fluorescence, B. melitensis, B. subtilis and P. aeroginosa individually showed 89%, 87%, 85% and 92% degradation, respectively, as compared to 34% in control after 30 days. Population dynamics of the introduced isolates based on antibiotic resistance survival and REP-PCR indicated 60-70% survival based on antibiotic resistance, but only 35-45% of the inoculated population based on REP-PCR. During bioremediation studies, 3,5,6-trichloro-2-pyridinol (TCP) was detected as metabolite of chlorpyrifos degradation by 1 aeroginosa after 20 days, which was utilized and disappeared after 30 days. Whole-cell studies also showed that P. aeroginosa gave TCP as the product of chlorpyrifos degradation, which was further metabolized to unknown polar metabolites. Scientific relevance: Potential application in sites for effective in situ bioremediation of chlorpyrifos, a neurotoxic insecticide widely used in India. (C) 2008 Elsevier Ltd. All rights reserved.