Home – Home – Jornals – Russian Geology and Geophysics 2001 number 11-12

The paper deals with the problem of bacterial oxidation (biodegradation) of crude oil hydrocarbons. The review of the literature on natural biodegraded oils and laboratory experiments suggest that the normal and branched alkanes are susceptible to microbiological degradation, as well as polycyclic saturated biomarker hydrocarbons (steranes, hopanes, and cheilanthanes). The homologous series of demethylated hopanes are assumed to be of different genesis: 28-norhopanes have the precursors in membranes of prokaryotes, i. e., they are "primary" biomarkers, while 25-norhopanes result from bacterial oxidation of regular hopanes in oil pools. Homohopanes close to "biological" structures (22R) are the first to be assimilated by bacteria. At the final stages of biodegradation, demethylation of cheilanthanes occurs at C-10. All this allows construction of the stage scale of hydrocarbon biodegradation.