Kinetic modelling, production optimization, functional characterization and phyto-toxicity evaluation of biosurfactant derived from crude oil biodegrading Pseudomonas sp. IITISM 19

Abstract

In the present study, the biosurfactant production dynamics of Pseudomonas sp. IITISM 19, an indigenous bacterium was investigated and, the strain was evaluated for its crude oil biodegradation potential. The biosurfactant produced during biodegradation was characterized by TLC, and NMR spectrophotometry as a lipopeptide. The biosurfactant production was modeled by the Luedeking-Piret model and found to have a value of 1.4961 for the growth associated constant α and a negative value for the non-growth associated constant β signifying that biosurfactant production was growth associated. The biosurfactant yield was statistically optimized to 3.45 g/L from 1.27 g/L using central composite design-response surface methodology after monitoring four individual growth parameters. Phytotoxic evaluation of the lipopeptide concluded that it was non-toxic for seed growth and germination even at the high concentration of 400 mg/L. The bacterial strain was efficient in the biodegradation of 64% of crude oil and the TPH degradation rate was observed to be 73% after 35 days. The bacteria grown on crude oil-containing medium showed a high amount of enzyme activity for AHs, ADHs, catalase, and lipase, indicating that the strain is efficient in treating crude oil and hydrocarbon pollution. The GCMS analysis of residual crude oil extracted after the biodegradation process identified several volatile fatty acids, carboxylic acids, benzoic acid, and phthalic acids as metabolites formed after oxidation of aromatic and aliphatic fractions of crude oil composition.