Enhanced biodegradation of endosulfan and its major metabolite endosulfate by a biosurfactant producing bacterium

Abstract

The present study was carried out to isolate bacteria capable of producing biosurfactant that solublize endosulfan (6,7,8,9,10,10-Hexachloro-1,5,5a,6,9,9a-hexahydro- 6,9-methano-2,4,3-benzodioxathiepine-3-oxide) and for enhanced degradation of endosulfan and its major metabolite endosulfate. The significance of the study is to enhance the bioavailability of soil-bound endosulfan residues as its degradation is limited due to its low solubility. A mixed bacterial culture capable of degrading endosulfan was enriched from pesticide-contaminated soil and was able to degrade about 80% of α-endosulfan and 75% of β-endosulfan in five days. Bacterial isolates were screened for biosurfactant production and endosulfan degradation. Among the isolates screened, four strains produced biosurfactant on endosulfan. ES-47 showed better emulsification of endosulfan and degraded 99% of endosulfan and 94% of endosulfate formed during endosulfan degradation. The strain reduced the surface tension up to 37 dynes/cm. The study reveals that the strain was capable of degrading endosulfan and endosulfate with simultaneous biosurfactant production.

Keywords:

• Biosurfactant
• biodegradation
• endosulfan
• bioavailability
• endosulfate
• pesticide degradation
• rhamnolipid

Acknowledgments

The authors thank University Grants Commission, New Delhi, India for the financial assistance provided for carrying out the present study. We gratefully acknowledge the assistance rendered by Mr. Thirunavukkarasu, Laboratory Assistant, Centre for Environmental Studies, Anna University, Chennai, India during the study.