Biosurfactant production by Pseudomonas sp. and its role in aqueous phase partitioning and biodegradation of chlorpyrifos

Aim:  To study the effect of biosurfactant on aqueous phase solubility and biodegradation of chlorpyrifos.
Methods and Results:  A Pseudomonas sp. (ChlD), isolated from agricultural soil by enrichment culture technique in the presence of chlorpyrifos, was capable of producing biosurfactant (rhamnolipids) and degrading chlorpyrifos (0·01 g l⁻¹). The partially purified rhamnolipid biosurfactant preparation, having a CMC of 0·2 g l⁻¹, was evaluated for its ability to enhance aqueous phase partitioning and degradation of chlorpyrifos (0·01 g l⁻¹) by ChlD strain. The best degradation efficiency was observed at 0·1 g l⁻¹ supplement of biosurfactant, as validated by GC and HPLC studies.
Conclusion:  The addition of biosurfactant at 0·1 g l⁻¹ resulted in more than 98% degradation of chlorpyrifos when compared to 84% in the absence of biosurfactant after 120-h incubation.
Significance and Impact of the Study:  This first report, to the best of our knowledge, on enhanced degradation of chlorpyrifos in the presence of biosurfactant(s), would help in developing bioremediation protocols to counter accumulation of organophosphates to toxic/carcinogenic levels in environment.