Isolation And Preliminary Application Of Methanogens From Diverse Anaerobic Environments

Methanoarchaea (Methanogen) are prominent members of the uryarchaeota kingdom. These fastidious anaerobe utilize simple compound as distinct substrates for carbon and energy generation. The anaerobic decomposition of biomass is an integral component of the global carbon cycle. Biological methanogenesis is the final step in the decomposition of biomass in many diverse anaerobic environments. The study of microbes that produce methane is important for the anaerobic decomposition of biomass. The research isolating methanogen from diverse anaerobic environments is to enrich the resources of methanogen and to select strains which have special characteristics. This research is also a preparation for the microorganism agent of biogas fermentation.Twelve methanogen were isolated, which ascribed three genera and six species, from the diverse anaerobic environments such as sediments of marine, anaerobic digesters, the pit mud of Chinese liquors. Ten hydrogenotrophic methanogen (designated JN432, 2522, JZYS, JZTM, 3#, 4#, NG-1, NG-2, JB-1, JB-2) and two acetotrophic and methylotrophic methanogens (designated Tf, 1923) , enriched the resources of methanogen. The thermophilic hydrogenotrophic methanogen JZTM genotypically ascribed to Methanobacterium thermoautotrophicum. But the morphology and growth conditions of strain JZTM are different from that Methanobacterium thermoautotrophicum deltH. Sequence analysis of the 16S rDNA revealed that the thermophilic hydrogenotrophic strains ZC-2, ZC-3 belonged to the genus Methanoculleus. On the basis of phenotypic, genotypic and phylogenetic characteristics, a novel species of Methanoculleus is proposed for strain ZC-2. Methanosarcina mazei strain 1923 could produce EPS(extracellular polysaccharides) in some growth phase. Between 25℃to 35℃the addition of the culture of strain 1923 led to 31% shrinkage in the startup time and 69.7% increase in biogas production in three months. Between 10℃to 20℃the content of volatile fatty acids deceased faster in reactor by the addition of the culture. It was the first time using pure culture of methanogens as additives for enhancing biogas fermentation in our country.