Rhamnolipid assisted degradation of petroleum crude oil by indigenous Pseudomonas sp. WDE11 in seawater

Abstract

Chronic and acute release of petroleum crude into oceans and seas leads to catastrophic effects on ecosystems and global climate. Employing effective strategies for the mitigation of petroleum crude pollution in the marine environment is the need of the hour. An indigenous strain of Pseudomonas (sp. WDE11), with polyaromatic hydrocarbon degrading abilities, degraded 1% petroleum crude oil (PCO) effectively in seawater on supplementation of glucose (1.0 g/L). Degradation was assisted by biosurfactant with low CMC (15.0 g/L) and was characterized as a rhamnolipid by FESEM-EDAX, LCMS, and FT-IR analysis. Glucose and inoculum depicted curvature amongst other tested parameters (incubation time, PCO, pH, and agitation speed via OPAT approach, and were subsequently optimized to maximum degradation using Pseudomonas sp. WDE11 by a 22 central composite design method. The highest degradation of 80 ± 0.15% of 1.0% PCO was achieved at 2.53 g/L glucose and 8.18% inoculum, as optimized conditions. GC/MS analysis depicted the degradation of all major hydrocarbons present in PCO on comparing with abiotic control. This study indicates the potential of Pseudomonas sp. WDE11 in the eradication of petroleum pollution from the contaminated marine environment under nutrient-limited conditions.