Study of the removal of a pesticides mixture by a Streptomyces strain and their effect on the cytotoxicity of treated systems

Abstract

Currently, organochlorine pesticides (OPs) are restricted or banned from agricultural and public health areas. However, many of these compounds have been found in high concentrations in contaminated sites, and therefore continue to pose environmental and health concerns. Thus, it is imperative to identify efficient microorganisms to remove them and to develop methods to remediate environments contaminated with OPs. In this regard, the aim of this work was to evaluate the individual and simultaneous removal of three OPs; specifically lindane (LIN), γ-chlordane (CLD) and methoxychlor (MTX) (2 mg L-1 of each pesticide alone or as constituent of a mixture), from liquid contaminated systems, employing a native and non-GMO Streptomyces strain. Toxicity test of the treated systems against the cell line Caco-2, and the detection in the genome of the used microorganism of sequences related with the pesticides catabolism are reported. The results demonstrated that, Streptomyces sp. A5 was able to remove individually 57.4%, 100.0% and 6.5% of LIN, CLD and MTX, respectively. From the pesticide mixture, LIN and CLD were efficiently removed on 62.2% and 68.6% respectively by the studied strain. On the other hand, we demonstrated that the liquid systems contaminated with the OPs mixture and bioremediated with Streptomyces sp. A5 showed lower cytotoxicity than their respective controls without inoculate. Moreover, molecular studies revealed the presence in Streptomyces sp. A5 of putative lin genes with potential dehydrochlorinase, haloalkane dehalogenase and NAD-dependent dehydrogenase activities. Therefore, the potential of Streptomyces sp. A5 to efficiently remediate OPs alone or in mixtures from liquid contaminated system, was demonstrated.