Halotolerant Gordonia sp. DH2 enhances hydrocarbon degradation and emulsification in high-salinity oil reservoirs through cell-associated surface-active material

Abstract

Gordonia sp. DH2 is a halotolerant hydrocarbon-degrading bacterium isolated from a petroleum reservoir. It effectively degraded alkanes and aromatic hydrocarbons and exhibited strong cell-associated emulsifying activity during hydrocarbon utilization. Whole-genome analysis revealed genes putatively associated with salt tolerance, hydrocarbon degradation and biosurfactant-related functions. The culture conditions affecting emulsifying activity were further investigated. Based on TLC staining and FTIR analysis, the extracted cell-associated surface-active material was inferred to contain carbohydrate-related and lipid-like moieties, suggesting a glycolipid-like surface-active fraction rather than permitting definitive structural identification. Unlike most reported extracellular biosurfactant-producing bacteria, Gordonia sp. DH2 exhibited an uncommon cell-associated emulsification phenotype, which enhanced adhesion to hydrophobic surfaces and promoted petroleum emulsification. The strain also showed strong degradation capacity toward both alkanes and aromatic hydrocarbons under saline conditions.