Oxidation syntrophic acetate

Galushko AS, Schink B. 2000. Oxidation of acetate through reaction of the citric acid cycle by Geobacter sulfurreducens in pure culture and in syntrophic coculture. Arch Microbiol 174 314-21. 

Kaden J., Galushko A. S., and Schink B. (2002) Cysteine-mediated electron transfer in syntrophic acetate oxidation by co-cultures of Geobacter sulfurreducens and Wolinella succinogenes. Arch. Microbiol. 178, 53—58. 

Furukawa Y, Inubushi K (2002) Feasible suppression technique of methane emission from paddy soil by iron amendment. Nutr Cycl Agroecosyst 64 193-201 Fuseler K, Krekeler D, Sydow U, Cypionka H (1996) A common pathway of sulfide oxidation by sulfate-reducing bacteria. FEMS Microbiol Lett 144 129-134 Galushko AS, Schink B (2000) Oxidation of acetate through reactions of the citric acid cycle by Geobacter sulfurreducens in pure culture and in syntrophic coculture. Arch Microbiol 174 314-321... 

Although this idea of a syntrophic association based on inter-species hydrogen transfer is very appealing, it explains only a part of the observations on AOM. Since both the methanotrophic archaea and the sulfate reducing bacteria carry the light carbon isotopic signal of methane, it is a question how also carbon is transferred in this syntrophic association. An alternative pathway could therefore be the conversion of methane to acetate and the subsequent oxidation of acetate (CH COO ) by the sulfate reducers with a concurrent incorporation of part of the acetate into their cell biomass ... 

This process is often called syntrophic acetate oxidation. When acetate is being reduced, the inverse reaction is running, called homoacetogenesis ... 

Cord-Ruwisch R., Lovley D. R., and Schink B. (1998) Growth of Geobacter sulfurreducens with acetate in syntrophic cooperation with hydrogen-oxidizing anaerobic partners. Appl. Environ. Microbiol. 64, 2232-2236. 

Lee M. J. and Zinder S. H. (1988) Isolation and characterization of a thermophilic bacterium which oxidizes acetate in syntrophic association with a methanogen and which grows acetogenically on H2-CO2. Appl. Environ. Microbiol. 54, 124-129. 

Zinder S. H. and Koch M. (1984) Non-aceticlastic methano-genesis from acetate acetate oxidation by a thermophilic syntrophic culture. Arch. Microbiol. 138, 263-272. 

Fig. 8.7 Schematic of AOM aggregate with a syntrophic metaholism among two members that only in combination can catalyze the complete oxidization of methane with sulfate. A transfer of or acetate (CHjCOO ) from methanotrophic archaea to sulfate reducing bacteria has been proposed as an intermediate in the net process. Such an interspecies transfer of hydrogen or organic carbon is still hypothetical and has not been directly demonstrated.

Summing up this reaction with reactions of butyrate and acetate oxidizing we get syntrophic interaction of two different species of bacteria ... 

Kimura Z, Okabe S. Acetate oxidation by syntrophic association between Geobacter sulfurreducens and a hydrogen-utilizing exoelectrogen. ISME J 2013 7 1472-1482. 

---