Isolation of pesticide-degrading actinomycetes from a contaminated site: Bacterial growth, removal and dechlorination of organochlorine pesticides

Organochlorine pesticides are notorious, due to their high toxicity, persistence in the environment and their tendency to bioaccumulate. Their extensive use in the northwest of Argentina has left residues in the environment. Microbial degradation is an important process for pesticide bioremediation and actinomycetes have a great potential for that. The current study examined organochlorine pesticides in contaminated soil. Indigenous actinomycetes were isolated from contaminated samples to evaluate bacterial growth as well as pesticide removal and release of chloride ions as a result of degradation. Most of the isolated microorganisms belonged to the Streptomyces genus, except one, which belonged to Micromonospora. Bacterial growth depended on the microorganism and the pesticide present (chlordane, lindane or methoxychlor). Highest growth and pesticide removal were observed with chlordane. Twelve out of 18 studied strains released chloride into culture supernatants, and percentages were higher with chlordane as carbon source than with lindane or methoxychlor. These results are supported by principal component analysis. This is the first report about actinomycetes isolated from an illegal storage of organochlorine pesticide in Argentina with capacity to growth, remove and use different organochlorine pesticide. (C) 2010 Elsevier Ltd. All rights reserved.