Effects of selective methanogenic inhibitors on methanogenesis and methanogenic communities in acetate degrading cultures

Abstract:

Abstract:［Objective］We evaluated the role of syntrophic acetate oxidation coupled with hydrogenotrophic methanogens in three different methanogenic consortia．［Methods］Three methanogenic hexadecane degrading consortia named Y15，M82 and SK were taken from the same oily sludge of Shengli oil-field and enriched．They were incubated at 15，35 and 55℃，respectively．The consortia amended with acetate and inhibitors of NH4 Cl or CH3 F were further transferred and incubated at corresponding temperatures．The cultures atlate logarithmic phase were collected for terminal restriction fragment length polymorphism (T-RFLP) combined with cloning and phylogenetic analysis of 16S rRNA gene fragments． ［Results］Gas chromatograph analysis showed that all of the consortia could grow and produce methane，but the lag phase was delayed and the growth rate was retarded in the cultures amended with inhibitor． Combination analysis of T-RFLP and clone library revealed the predominance of obligate aceticlastic Methanosaeta in the acetate cultures of Y15，M82 and SK．Under the mesophilic and thermophilic conditions，after add inginhibitor the relative abundance of aceticlastic methanogen decreased but hydrogenotrophic methanogen increased．［Conclusion］Syntrophic acetate oxidation during methanogenic degradation of petroleum hydrocarbons occurs under mesophilic and thermophilic conditions，although the situation at low temperature seems uncertain．