Degradation of polyaromatic hydrocarbons employing biosurfactant-producing Bacillus pumilus KS2

Abstract

An efficient hydrocarbon-degrading native bacterial strain Bacillus pumilus KS2 (identified by partial 16S rDNA gene sequencing) was isolated from crude oil-contaminated soil collected from oil fields of Lakowa, Sivasagar district of Assam, India. Experiments were conducted under laboratory conditions to determine the efficiency of this biosurfactant-producing strain to degrade polycyclicaromatic hydrocarbons (PAHs). Quantification of the capacity of the biosurfactant to reduce the surface tension (ST) of the culture medium was used as a measure of biosurfactant production. In terms of total petroleum hydrocarbon (TPH) degradation, strain KS2 was able to degrade 80.44 % of the TPH by 4 weeks of incubation. It also demonstrated efficient degradation of PAHs, completely degrading nine of the 16 major PAHs present in the crude oil sample. Strain KS2 also produced biosurfactant which, based on biochemical and FTIR analyses, was glycolipid in nature. To our knowledge, this is the first report showing the potential of a native strain of the North-East region of India for efficient degradation of TPH and PAHs and, consequently, in the remediation of hydrocarbons from contaminated sites.