Comparative characterization of anaerobic oil oxidation processes by microbial communities of sediments from natural oil seeps in Lake Baikal (Gorevoy Utes, Bolshaya Zelenovskaya)

Abstract

The comparative characterization of oil biodegradation processes under anaerobic conditions during the cultivation of microbial communitiesof sediments from two sites of oil seeps is given. The microbial community of sediments from the Bolshaya Zelenovskaya River oil seep, functioning under the conditions of long-term exposure to hydrocarbons, is focused more on the processes of anaerobic oxidation of oil in comparison with the microbial communities of sediments from the oil seep located near Cape Gorevoy Utes. This is evidenced by the high level of hydrocarbon biodegradation in both surface and deep sediments, regardless of the electron acceptors present in the medium. Oil degradation in enrichment cultures was accompanied by the formation of hydrocarbon gases (methane and ethane). The highest concentration of methane formed was found in the experiment with sediments from Cape Gorevoy Utes. Ethane generation, on the contrary, was more typical of the cultivation of communities from sediments of the Bolshaya Zelenovskaya River. Microbial communities functioning under anaerobic conditions in sediments at the sites of oil seeps are no less important in the processes of self-purification of the lake from oil “pollution” than aerobic microbial communities of the water column and surface sediments.