Degradation of acetochlor by a bacterial consortium of Rhodococcus sp.T3-1, Delftia sp.T3-6 and Sphingobium sp.MEA3-1

Abstract

Owing to acetochlor persistence in the environment and its perceptible threats to the ecosystem and human health, it is urgent to search for effective approaches to decontaminate acetochlor. In this study, an acetochlor-degrading enrichment culture was obtained by continuous enrichment from acetochlor-contaminated soil and named T3. T3 could completely degrade 100 mg l(-1) acetochlor and butachlor within 6 days. Two bacterial strains Rhodococcus sp.T3-1 and Delftia sp.T3-6 and one strain Sphingobium sp.MEA3-1 were isolated and identified from T3 by using acetochlor and MEA as sole carbon source, respectively. These three bacteria could completely mineralize acetochlor by the cooperative metabolism. The biochemical pathway of acetochlor degradation by these three bacteria in a consortium was proposed: acetochlor to 2'-methyl-6'-ethyl-2-chloroacetanilide (CMEPA) by Rhodococcus sp. T3-1, CMEPA to 2-methyl-6-ethyl aniline (MEA) by Delftia sp.T3-6 and MEA by Sphingobium sp.MEA3-1 based on the identified degradation intermediates. Under laboratory conditions, the consortium was effective in the acetochlor mineralization. This study presents a bacterial consortium consisting of Rhodococcus sp.T3-1, Delftia sp.T3-6 and Sphingobium sp.MEA3-1 could completely mineralize acetochlor by biochemical cooperation. The study reveals the metabolic mechanism of acetochlor biodegradation and highlights the potential of the bacterial consortium for cleaning up acetochlor and its metabolites subsisting in the environment.