Investigation of the trophic relations between anaerobic microorganisms from an underground gas repository during methanol utilization

Abstract

Joint cultivation of the dominant strains of acetogenic, sulfate-reducing and methanogenic microorganisms isolated from water samples of the North Stavropol underground gas storage facility (UGSF) was carried out for revealing their probable trophic relationships. It was shown that acetogenic strains Eubacterium limosum AG12 and Sporomusa sphaeroides AG8-2 growing on methanol could form a considerable pool of hydrogen, which may support development of hydrogenotrophic cultures, the methanogen Methanobacterium formicicum MG134, or the sulfate reducer Desulfovibrio desulfuricans SR12. Growth of this sulfate-reducing strain was not stimulated under joint cultivation with Methanosarcina barkeri MGZ3 on methanol, probably due to its inability to take up low hydrogen concentrations observed during methanosarcina development. The results show that acetogens in the UGSF system are the most important consumers of methanol and hydrogen and after exhaustion of the latter and switching over to methanol utilization they can supply hydrogen to other microorganisms, including methanogens and sulfate reducers. The role of methanosarcina in the UGSF increases as the hydrogen and CO2 reserves are exhausted, and methanogenesis on methanol becomes the main way of its destruction.