Formation of Petroleum Hydrocarbons from Prokaryote Biomass: 3. Formation of Petroleum Biomarker Hydrocarbons from Biomass of Shewanella putrefaciens Bacteria and Asphaltenes Isolated from Crude Oil

The distribution of saturated biomarker hydrocarbons (n-alkanes, isoprenanes, steranes, terpanes) in extracts of the soluble part and thermolysis products of the insoluble part of biomass of the Shewanella putrefaciens bacteria isolated from crude oil of the Dagang field and in the products of thermolysis of asphaltenes from the same oil have been studied by gas chromatography-mass spectrometry. The homologous series of C-10-C(36)n-alkanes and C-11-C-20 isoprenanes and squalene have been found among aliphatic hydrocarbons (HCs) in the extracts and the thermolysis products of the insoluble part. Various n-alkanes predominate in the extracts collected at different times, while the value of the pristane/phytane genetic index corresponds to marine organic matter (OM) in all the cases. Petroleum steranes and terpanes are found among cyclic biomarker hydrocarbons, the distribution of which in the thermolysis products of the insoluble part of the biomass is close to the petroleum distribution. The relative concentration of n-alkanes in the products of thermolysis of asphaltenes prevails over the relative concentration of isoprenanes. It has been assumed that the Shewanella putrefaciens biomass made a certain contribution to the formation of the biomarker hydrocarbons of the Dagang oil.