Isolation and characterization of a thermophilic bacterium which oxidizes acetate in syntrophic association with a methanogen and which grows acetogenically on H/sub 2/-CO/sub 2/
The authors previously described a thermophilic (60/sup 0/C), syntrophic, two-membered culture which converted acetate to methane via a two-step mechanism in which acetate was oxidized to H/sub 2/ and CO/sub 2/. While the hydrogenotrophic methanogen Methanobacterium sp. strain THF in the biculture was readily isolated, we were unable to find a substrate that was suitable for isolation of the acetate-oxidizing member of the biculture. In this study, we found that the biculture grew on ethylene glycol, and an acetate-oxidizing, rod-shape bacterium (AOR) was isolated from the biculture by dilution into medium containing ethylene glycol as the growth substrate. When the axenic culture of the AOR was recombined with a pure culture of Methanobacterium sp. strain THF, the reconstituted biculture grew on acetate and converted it to CH/sub 4/. The AOR used ethylene glycol, 1,2-propanediol, formate, pyruvate, glycine-betaine, and H/sub 2/-CO/sub 2/ as growth substrates. Acetate was the major fermentation product detected from these substrates, except for 1,2-propanediol, which was converted to 1-propanol and propionate. N,N-Dimethylglycine was also formed from glycine-betaine. Acetate was formed in stoichiometric amounts during growth on H/sub 2/-CO/sub 2/, demonstrating that the AOR is an acetogen. This reaction, which was carried out by the pure culture of the AOR in the presence of high partial pressures of H/sub 2/, was the reverse of the acetate oxidation reaction carried out by the AOR when hydrogen partial pressures were kept low by coculturing it with Methanobacterium sp. strain THF. The DNA base composition of the AOR was 47 mol% guanine plus cytosine, and no cytochromes were detected.
- Research Organization:
- Cornell Univ., Ithaca, NY
- OSTI ID:
- 5270697
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 54:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
09 BIOMASS FUELS
ACETATES
OXIDATION
METHANE
BIOSYNTHESIS
ANAEROBIC CONDITIONS
BACTERIA
CARBON DIOXIDE
HYDROGEN
METHANOGENIC BACTERIA
THERMOPHILIC CONDITIONS
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACID SALTS
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
HYDROCARBONS
MICROORGANISMS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SYNTHESIS
550700* - Microbiology
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140504 - Solar Energy Conversion- Biomass Production & Conversion- (-1989)