Aerobic removal of methoxychlor by a native Streptomyces strain: Identification of intermediate metabolites

Abstract

Streptomyces strains isolated from pesticide-contaminated sediments of Santiago del Estero, Argentina were able to grow in the presence of 1.66 mg L−1 of methoxychlor (MTX). Streptomyces sp. A14 showed the best growth in the presence of MTX in culture medium at 30 °C and pH 7. When soil microcosms were contaminated with MTX and inoculated with Streptomyces sp. A14, a decrease in MTX was detected in both concentrations assayed (8.33and 16.60 mg kg−1). This actinobacterium was able to remove the pesticide, reaching its maximum removal percentages (40% and 76%) after 28 days of incubation. Methoxychlor was gradually converted into 1,1-dichloro-2,2-bis(4-methoxyphenyl)ethane, 1,1-dichloro-2,2-bis(4-methoxyphenyl)ethylene, 1-chloro-2,2-bis(4-methoxyphenyl)ethane, and 2,2-bis(4-hidroxyphenyl)acetonitrile, indicating that MTX is dominantly degraded by dechlorination, dehydrogenation and CN-replacement, resulting in the production of several major degradation products. This is an interesting proposal as an alternative method for soil cleanup. This is the first report of methoxychlor degradation using a native Streptomyces strain under aerobic conditions.