Screening of a glycolipid biosurfactant-producing strain for kerogen biodegradation

Abstract:

[Objective] Biosurfactant-producing strains were screened from an oil-shale environment for the biodegradation of kerogen in oil shale. [Methods] Wastewater samples of the Fushun oil-shale mine were collected and used for the primary screening of biosurfactant-producing strains using the blood-agar plate method. Oil spreading, emulsification activity, and surface tension methods were further used to re-screen the biosurfactant-producing strains. The target strain was identified by 16S rRNA gene sequencing and phylogenetic analysis, as well as by determining its physiological and biochemical characteristics. Surface-active components in the zymotic fluid of the target strain were analyzed by thin-layer chromatography. The culture conditions were optimized for biosurfactant production by the target strain, and its biodegradation of oil-shale kerogen was examined preliminarily. [Results] A glycolipid biosurfactant-producing strain, B-1, was screened and identified preliminarily as a Pseudomonas sp., and it showed the advantages of good oil displacement and emulsifying ability, and low surface tension. Strain B-1 used alkanes, unsaturated fatty acids, and carbohydrates as carbon sources. In a glucose-containing culture medium (pH 7.0) with 0.3% NaCl, strain B-1 grew well at 30?34 °C, and the surface tension of the zymotic fluid exhibited its lowest value (27 mN/m). After 30 d, the kerogen degradation rate of strain B-1 in the glucose-containing medium was 2.85%, compared with 1.04% in a control medium without glucose. [Conclusion] Strain B-1 is a good glycolipid biosurfactant-producing bacterium with the potential to degrade kerogen.