Biochemical Characterization of a Novel Lipopeptide Biosurfactant Produced by Rhodococcus pyridinivorans SK12 and its Application in Crude Oil Biodegradation

Crude oil and petroleum hydrocarbons are recalcitrant and persistent organic pollutants discharged into the environment during petrochemical exploration, production, storage and spills. In this research, a novel bacterial strain Rhodococcus pyridinivorans SK12, was isolated from crude oil polluted soil samples and characterized for its ability to produce an effective biosurfactant for crude oil bioremediation. An efficient biodegradation of upto 95.51 ± 4.33% of crude oil (2% v/v) was achieved by the bacterial strain SK12 within 6 days of incubation at 37 °C in minimal medium. While the Rhodococcus species are well known to produce rhamnolipid biosurfactants, the bacterium SK12 produced a unique lipopeptide biosurfactant linked with polysiloxane moieties as determined by Gas Chromatography-Mass Spectrometry (GC-MS), Fourier Transform-Nuclear Magnetic Resonance (FT-NMR), and Fourier Transform-Infrared (FT-IR) Spectroscopy. Biochemical composition of the biosurfactant mainly consisted derivatives of octadecanoic acid, hexadecanoic acid, tetradecanoic acid, acetic acid, sulfur containing amino acid, amines and siloxane compounds. The critical micelle concentration (CMC) of the biosurfactant was determined to be 33 mg/L. These results show that the novel lipopeptide biosurfactant producing strain R. pyridinivorans SK12 is a promising agent for use in crude oil bioremediation.