f Distribution of Methanogens in Petroleum Reservoirs of Garzan, Dodan, Silivanka, Çamurlu Areas

Petroleum reservoirs are important natural habitats for microorganisms. Biodegradation of petroleum results in a decrease in its hydrocarbon content and an increase in oil density, sulphur content, acidity and viscosity. These changes have negative economic consequences for oil production and refining operations. It has been established that methanogens constitute an important microbiological community inhabiting oilfields. Petroleum hydrocarbons (PHC) are degraded to methanogenic substrates such as acetate, CO2, and H2 by diverse bacteria, and methanogenesis is a final degradation process of organic matter by methanogenic archaea in anoxic petroleum reservoir environments.There is a limited information about petroleum biodegredation of methanogens. It is important to develop a method for methanogens activity and determine the effects of methanogens in this environment. The aim of this study was to determine the distribution of metanogens in petroleum reservoirs. For this purpose oil samples were collected (9 petroleum and 5 petroleum-water phase) from Garzan, Dodan, Silivanka and Çamurlu areas. Samples were inoculated in media under pure gases N2. After then inoculated samples were gassed with H2-CO2 (80:20) atmosphere. All incubations were made in the dark at 30ºC for 21 days. Methane was measured by gas chromatograph. It was found that methanogens were isolated only one out of 9 petroleum (10 cell ml-1) and two out of 5 petroleum-waterphase (15 cell ml-1). These results showed that petroleum reservoirs contain a low number of methanogen but this results should be supported by molecular methods. It is important to understand the ecology of methanogens in petroleum reservoir. In future studies, molecular techniques should be applied to characterize methanogens in petroleum reservoirs in Turkey.