Screening and product identification of biosurfactant-producing strains in crude oil-contaminated soil

Abstract:

[Objective] To screen out a surfactant-producing microbial strain Bacillus subtilis SX-20 from the soil contaminated by crude oil for a long time and then extract and analyze the products of the strain. [Methods] We used cetylpyridinium chloride-brominated thymol blue combined with blood agar plate for the screening and obtained a strain capable of producing lipopeptide. The crude fermentation product of the strain was extracted by acid precipitation, methanol extraction, and rotary evaporation, and it showed good inhibitory effect on Propionibacterium acnes. Its composition was analyzed by Fourier transform infrared spectroscopy (FTIR), amino acid analysis, and liquid chromatography-mass spectrometry (LC-MS). [Results] The surfactant-producing strain screened out was identified as Bacillus subtilis and named SX-20. The product of the screened strain was a cyclic lipopeptide containing a C15 fatty acid chain and 7 amino acid residues. [Conclusion] This study provided a theoretical basis and technical route for the screening of biosurfactant-producing strains, which is conducive to the subsequent acquisition of high-yield and low-cost biosurfactants.

Key words:crude oil-contaminated soil;Bacillus subtilis;surfactant;lipopeptide;screening;identification