AbstractThree endosulfan-degrading bacterial strains, Pseudomonas sp. KT1, Pseudomonas sp. KT2 and Staphylococcus sp. DKT, were isolated and investigated for their degradation under anaerobic conditions. These bacteria effectively degraded endosulfans and some related compounds. All of the isolates utilized nitrate as an electron acceptor and nitrogen source. Endosulfans degradation performances by a mixed culture of Pseudomonas sp. KT2 and Staphylococcus sp. DKT changed from 25.9 ± 4.5 to 34.0 ± 5.5% and were higher than the degradation by the each individual strain. Moreover, Pseudomonas sp. KT2 was the first pure culture capable of degrading a persistent compound, endosulfan sulfate, under anaerobic conditions. The determination of degradation metabolites showed that endosulfan diol, endosulfan ether and endosulfan lactone were formed during endosulfan degradation by Pseudomonas sp. KT1 and KT2. Dehalogenase extracted from mixed culture cells also revealed effective degradation and dechlorination. The results in this study show that a mixed culture was valuable for biodegradation of endosulfans and some of their relatives under anaerobic conditions.