Characterization of a new biosurfactant produced by an effective pyrene-degrading Achromobacter species strain AC15

An Achromobacter species strain AC15 was isolated from mangrove soil and identified as a potent producer of biosurfactant. It could utilize high concentrations of pyrene as the sole source of carbon and energy. Results showed that AC15 degraded about 40% of the pyrene, which was provided at an initial concentration of 300 mg L−1, and reduced surface tension of the culture medium from 67.2 to 33.2 mN m−1 after 14 d of incubation using its good emulsification property on the culture medium. The main chemical component of partially purified biosurfactant, namely BS15, was analyzed by gas chromatography-mass spectrometry, amino acid analysis, and LTQ Orbitrap Elite mass spectrometry. Results showed that BS15 was a novel linear lipopeptide with a long-chain C16 fatty acid and peptide comprised of four amino acid residues. The molecular structure was determined as CH3-(CH2)14–CO–O-Leu-Asp-Lys-Ser. The solubility of pyrene in water improved 1.5–1.9 times in the presence of 40–60 mg L−1 of BS15. This work demonstrated that strain AC15 and its biosurfactant BS15 could be potential candidates in further applications of bioremediation of high-molecular weight polycyclic aromatic hydrocarbons.