Investigation of saturated and aromatic hydrocarbon resistance mechanisms in Pseudomonas aeruginosa IBBML1

Abstract

Abstract Pseudomonas aeruginosa IBBML1, isolated from Poeni petroleum sludge, was able to tolerate and degrade both saturated (n-hexane, n-heptane, n-hexadecane, cyclohexane) and aromatic (benzene, ethylbenzene, propylbenzene, xylene isomers, styrene) hydrocarbons. Molecular studies have revealed that the high hydrocarbon resistance of Pseudomonas aeruginosa IBBML1 could be due to the action of members of the HAE1 (hydrophobe/amphiphile efflux 1) family of transporters. It is further possible that additional mechanisms may account for the tolerance of Pseudomonas aeruginosa IBBML1 to hydrocarbons, and a combination of short-term and long-term mechanisms may act together in the adaptation of Pseudomonas aeruginosa IBBML1 cells to saturated and aromatic hydrocarbons. β-galactosidase activity measurements revealed that there was significant induction of the lacZ gene in Pseudomonas aeruginosa IBBML1 cells grown in the presence of either 5% and 10% (v/v) saturated or aromatic hydrocarbons, compared with control (cells incubated without hydrocarbons). Rhodamine 6G accumulation in Pseudomonas aeruginosa IBBML1 cells grown in the presence of 5% and 10% (v/v) saturated hydrocarbons was higher than rhodamine 6G accumulation in cells grown in the presence of 5% and 10% (v/v) aromatic hydrocarbons. The study of cellular and molecular modifications to Pseudomonas aeruginosa IBBML1 induced by 5% and 10% (v/v) saturated and aromatic hydrocarbons revealed a complex response of bacterial cells to the presence of different hydrophobic substrates in the culture medium.