Isolation and characterization of a Mycobacterium strain that metabolizes the insecticide endosulfan

Abstract

Aim: The aim of this study was to isolate and characterize a bacterium capable of metabolizing endosulfan. Methods and Results: A endosulfan-degrading bacterium (strain ESD) was isolated from soil inoculum after repeated culture with the insecticide as the sole source of sulfur. Analysis of its 16S rRNA gene sequence, and morphological and physiological characteristics revealed it to be a new fast-growing Mycobacterium, closely related to other Mycobacterium species with xenobioticdegrading capabilities. Degradation of endosulfan by strain ESD involved both oxidative and sulfur-separation reactions. Strain ESD did not degrade endosulfan when sulfite, sulphate or methionine were present in the medium along with the insecticide. Partial degradation occurred when the culture was grown, with endosulfan, in the presence of MOPS (3-(N-morpholino)-propane sulphonic acid), DMSO (dimethyl sulfoxide), cysteine or sulphonane and complete degradation occurred in the presence of gutathione. When both beta-endosulfan and low levels of sulphate were provided as the only sources of sulfur, biphasic exponential growth was observed with endosulfan metabolism being restricted to the latter phase of exponential growth. Conclusions: This study isolated a Mycobacterium strain (strain ESD) capable of metabolizing endosulfan by both oxidative and sulfur-separation reactions. The endosulfan-degrading reactions are a result of the sulfur-starvation response of this bacterium. Significance and Impact of the Study: This describes the isolation of a Mycobacterium strain capable of degrading the insecticide endosulfan. This bacterium is a valuable source of enzymes for use in enzymatic bioremediation of endosulfan residues.

Esterase-based metabolic resistance to insecticides in heliothine and spodopteran pests

“…Redox reactions are known in bacteria that can degrade and detoxify endosulfan but to the best of our knowledge, no hydrolytic mechanism for degrading this insecticide has been characterised in any organism to date. 75,76) Nor is it obvious at this point how endosulfan could bind to and be sequestered by an overexpressed esterase, although we have found at least one other report of competitive inhibition of heliothine esterases by another organochlorine (in that case, DDT). 22) Interestingly, there is evidence that esterase-mediated SP resistance in H. armigera leads to negative cross-resistance to the oxadiazine indoxacarb.…”

Biodegradation and bioremediation of pesticide in soil: concept, method and recent developments

“…In another example i.e. lindane [18], endosulfan [19,20], DDT [21] and monocrotophos [22,23], the microbes and/or enzymes were isolated and identifi ed. Genetic studies of microbial degradation indicates that the plasmids are the main place for the gene of interest usually spread throughout the microbial community.…”

“…Genetic studies of microbial degradation indicates that the plasmids are the main place for the gene of interest usually spread throughout the microbial community. Sutherland et al [19] had reported Esd gene that had same sequence homology to monooygenase family that use reduced fl avin, provided by a separate fl avin reductase enzyme, as cosubstrates in Mycobacterium smegmatis. Esd catalyzes the oxygenation of β-endosulfan to endosulfan monoaldehyde to endosulfan hydroxyether.…”

A Single Monooxygenase, Ese, Is Involved in the Metabolism of the Organochlorides Endosulfan and Endosulfate in an Arthrobacter sp

“…It is therefore important in the management of pest species. However, endosulfan is extremely toxic to fish and aquatic invertebrates, and this has led to an interest in postapplication detoxification of this insecticide (27)(28)(29)(30).Commercial endosulfan is a mixture of two diastereoisomers (approximately 30% ␤-endosulfan and 70% ␣-endosulfan) which differ dramatically in their physicochemical and environmental properties (31). The environmental dispersion pathways include hydrolysis of the sulfur moiety to nontoxic endosulfan diol or oxidation to endosulfate.…”