Biodegradation of α- and β-hexachlorocyclohexane by Indigenous Actinobacteria

Abstract

The organochlorine pesticide lindane (γ-HCH,) and its non-insecticidal isomers α-, β-, and δ- continue to pose serious environmental and health concerns, although their use has been restricted or completely banned for decades. The present study reports the first results on the ability of Actinobacterias strains, isolated from a HCH-polluted site, to grow in a minimal medium containing α-, β-, HCH (8.3 mgL−1) as sole source of carbon. Growth of cultures and HCHs degradation by Streptomyces sp. M7 was investigated after 1, 2, 3, and 4 days of incubation by dry weight and GC with ECD detection, respectively. Streptomyces sp. M7 is able to metabolize the HCHs: removed to 100% of a-HCH and 55% of b-HCH in the optimal culture conditions: 30 ºC, pH 7 and the isomers maxima concentration of 8.3 mg L-1. Also, Streptomyces sp. M7 showed greater overall growth in the presence of a-HCH than b-HCH that the only carbon source, which is associated with total or partial removal of the isomers respectively.