Catabolic activity of Bacillus licheniformis and Desulfotomaculum ruminis bacteria in media containing rape-seed oil methyl esters ( RMe) has been studied. The degree of the esters’ biodegradation was assessed on the basis of the kinetic parameters of the process of microbiological reduction of nitrates or sulphates, taking place with the involvement of RMe as electron donors. It has been shown that RMe in a wide range of concentrations are effective sources of carbon and energy for Bacillus licheniformis bacteria. At the esters concentration of 0.3% in the medium, the conversion of nitrates reached 100%, COD was reduced by 80% (biodegradation of RMe) and biomass increases three times. Desulfotomaculum ruminis bacteria in the media with RMe probably needs a long period of adaptation to this carbon source in the medium.