Effect of biosurfactant on biodegradation of heteroatom compounds in heavy oil

The ability of biodegradation on heavy components in heavy oil is still a controversial issue, and the effect of biosurfactants on resins is unclear. Four strains and biosurfactant were used to investigate the degradation ability of resins using gas chromatography-mass spectrometry (GC-MS) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) by a stimulated aerobic biodegradation experiment. Results showed that the biosurfactant improved biodegradation rates for saturates, aromatics, resins, and asphaltenes by 115-231%, 130-168%, 116-161%, and 135-217%, respectively. The A/C value (the sum of relative abundance of the acyclic O2 species divided by the sum of relative abundance of the mono, di- and tri-cyclic acids) indicated that biosurfactants could accelerate the biodegradation process. Results also showed that the utilization preference of O-containing and N-containing compounds varies from different strains by analysing their distribution. A reduction in the relative abundance of N1O1 class was detected in all samples containing microorganisms only. A significant decrease in C27H48O and C28H50O was observed in all samples with the biosurfactant. Carbazoles, benzocarbazoles and dibenzocarbazaoles could be effectively used by the strain J2 with biosurfactant. The relative abundance of O1 class increased when treated with microorganisms only. However, it decreased in the presence of biosurfactants. Therefore, biosurfactant could alter the preference that microorganism utilized heteroatom compounds.