Image courtesy of Mike McInerney

Syntrophomonas wolfeii subspecies wolfeii , Göttingen (G311), DSM2245B (Bacteria, 2.8 MB): anaerobic, mesophilic, syntrophic, hydrogen/formate-producing, fatty acid degrader; lives with methanogens.

Methanogenesis is a globally important process in the carbon cycle and has long been used to convert sewage and other wastes into the energy-rich compound, methane. Fatty and aromatic acids are key intermediates in methanogenesis and their degradation by syntrophic bacteria is thermodynamically unfavorable unless a second species, usually a methanogen, maintains H 2 and/or formate concentrations produced by the syntrophic bacterium at very low levels. This thermodynamically based interaction is called syntrophy. Genomic and functional genomic knowledge of the interactions between syntrophic and methanogenic microbes and the environmental controls on their regulatory and catalytic processes can be used to manage ecosystems to reduce greenhouse gas emissions and to enhance biological methane production from industrial and municipal wastes. Syntrophic consortia are ideal systems to study multispecies microbial assemblages since the thermodynamic constraints of metabolism forces tight kinetic coupling between the partners. Thus, while syntrophic associations are composed of metabolically diverse microorganisms, they function as a single catalytic unit. Syntrophic associations will provide an ideal model system for creating detailed molecular models of inter-cellular metabolic and regulatory networks (i.e., coupled networks between different organisms), a critical stepping stone for understanding how microbial communities exchange information and form distributed networks.

Syntrophomonas wolfeii strain Göttingen (DSM 2245B) degrades fatty acids from four to eight carbons in length in co-culture with hydrogen-using bacteria and some unsaturated fatty acids such as crotonate in pure culture. The organism is a curved rod with rounded ends and laterally inserted flagella on the convex side of the cell. S. wolfeii is a member of the family Syntrophomonadaceae , in the Gram-positive line of descent. This family is of particular phylogenetic interest because it includes bacteria whose cell wall ultrastructure resembles gram-negative bacteria, even though the 16S rDNA gene sequence analysis clearly place these organisms among gram-positive organisms.

Information the research community working on syntrophy.

Mike McInerney's laboratory studies the physiology of the fatty acids degrader, Syntrophomonas wolfeii, and the benzoate degrader, Syntrophus aciditrophicus . The whole genome sequencing and functional genomics of the latter organism is being directed by Rob Gunsalus. Fons Stams and Caroline Plugge are studying the physiology of Syntrophobacter fumaroxidans and the ecology of syntrophic bacteria in diverse habitats. Johannes Scholten and colleagues at Pacific Northwest National Laboratory are using functional genomic and computational approaches to study natural and constructed syntrophic associations to create detailed molecular models of inter-cellular metabolic and regulatory networks. Bernhard Schink's laboratory has made numerous contributions to the understanding of syntrophic metabolism; in particular, the development of bioenergetic models to explain how these bacteria obtain energy for growth from reactions that are close to thermodynamic equilibrium.   David Stahl's group at University of Washington and Lee Krumholz' group (University of Oklahoma) are both using functional genomics and molecular genetics to study syntrophic interactions between sulfate reducers and methanogens.

Relevant Literature:

Beaty, P. S. and M. J. McInerney. 1987. Growth of Syntrophomonas wolfei in pure culture on crotonate. Arch. Microbiol. 147:389-393.

M. J. McInerney, M. P. Bryant, and N. Pfennig. 1979. An anaerobic bacterium that degrades fatty acids in syntrophic association with methanogens. Arch. Microbiol. 122: 129-135.

M. J. McInerney, M. P. Bryant, R. B. Hespell, and J. W. Costerton. 1981. Syntrophomonas wolfeii   gen. nov., sp. nov., an anaerobic, syntrophic fatty acid-degrading bacterium. Appl. Environ. Microbiol. 41: 1029-1039.

Schink, B. 1997. Energetics of syntrophic cooperation in methanogenic degradation. Microbiol. Mol. Biol. Rev. 61:262-80.

Stams, A. J. M. 1994. Metabolic interactions between anaerobic bacteria in methanogenic environments. Antonie Van Leeuwenhoek 66:271-94.

Zhao, H., D. Yang, C. R. Woese, and M. P. Bryant. 1993 . Assignment of fatty acid-ß-oxidizing syntrophic bacteria to Syntrophomonadaceae   fam. nov. on the basis of 16S rRNA sequence analysis. Int. J. Syst. Bacteriol. 43 : 278-286 .