Metabolic characteristics of an aerobe isolated from a methylotrophic methanogenic enrichment culture

Abstract

An anaerobic methylotrophic methanogenic enrichment culture, with sustained metabolic characteristics, including that of methanation for over a decade, was the choice of the present study on interspecies interactions. Growth and methanation by the enrichment were suppressed in the presence of antibiotics, and no methanogen grown on methanol could be isolated using stringent techniques. The present study confirmed syntrophic metabolic interactions in this enrichment with the isolation of a strain of Pseudomonas sp. The organism had characteristic metabolic versatility in metabolizing a variety of substrates including alcohols, aliphatic acids, amino acids, and sugars. Anaerobic growth was favoured with nitrate in the growth medium. Cells grown anaerobically with methanol, revealed maximal nitrate reductase activity. Constitutive oxidative activity of the membrane system emerged from the high-specific oxygen uptake and nitrate reductase activities of the aerobically and anerobically grown cells respectively. Cells grown anaerobically on various alcohols effectively oxidized methanol in the presence of flavins, cofactor FAD and the methanogenic cofactor F420, suggesting a constitutive alcohol oxidizing capacity. In cells grown anaerobically on methanol, the rate of methanol oxidation with F420 was three times that of FAD. Efficient utilization of alcohols in the presence of F420 is a novel feature of the present study. The results suggest that utilization of methanol by the mixed culture would involve metabolic interactions between the Pseudomonas sp. and the methanogen(s). Methylotrophic, methanogenic partnership involving an aerobe is a novel feature hitherto unreported among anaerobic syntrophic associations and is of ecological significance

Influence of oxygen on the vinyl acetate elimination pathway and microbial community structure of methanogenic sludge

“…These results show evidence that aerobic‐methanogenic biomass carried out the hydrolysis of VA by an aerobic metabolic pathway, since without azide the VA was simultaneously mineralized and methanized, allowing to overcome the limiting step for their total elimination (Greń et al, 2011; Lara‐Mayorga et al, 2010). There are reports on the isolation of strict and facultative aerobic bacteria from anaerobic sludge, involved in the metabolism when sludge is fed low DO concentrations (Ouattara et al, 2003; Rapheal et al, 2003).…”

Changes in the Substrate Source Reveal Novel Interactions in the Sediment-Derived Methanogenic Microbial Community

“…Methanogenesis is a multistage process in which degradation of complex organic molecules into simple one-carbon compounds is performed by a consortium of microorganisms [7,8]. Their existence in the natural environment is an effect of coevolution leading to the development of metabolic interactions that allow the flow of carbon, energy, and other intermediates for mutual benefit [9,10]. The best recognized methanogenic Archaea belong to the phylum Euryarchaeota and are classified into seven orders, namely Methanococcales , Methanobacteriales , Methanosarcinales , Methanomicrobiales , Methanopyrales , Methanocellales , and Methanomassiliicoccales [11]; yet, additional new phyla, namely Bathyarchaeota [12] and Verstraetearchaeota [13], have been postulated.…”