Heavy hydrocarbon degradation of crude oil by a novel thermophilic Geobacillus stearothermophilus strain A-2

Thermophilic hydrocarbon-degrading microbial strains are particularly suited to improve the oil recovery process in high temperature reservoirs. In the present study, the effects of the thermophilic hydrocarbon-degrading Geobacillus stearothermophilus strain A-2 on heavy crude oil were investigated in terms of oil emulsification, changes in the oil viscosity and hydrocarbons degradation. Strain A-2 was isolated from the Dagang petroleum reservoir. Strain A-2 has strong surface hydrophobicity, and produces a bioemulsifier. The fermentation broth of strain A-2 caused the oil to disperse, and decreased the oil viscosity from 1540 mPa s to 923 mPa s. Strain A-2 preferentially degrades n-alkanes and aromatic hydrocarbons. In particular strain A-2 prefers the long-chain n-alkanes (>C21), naphthalene and methylated phenanthrene, and the highest degradation rate was 89.83% when cultured with C28 as a sole carbon source. Collectively, Geobacillus stearothermophilus strain A-2 showed its potential application for improving oil exploration in high-temperature oil reservoirs by improving the oil's properties.