title: The genome of Syntrophomonas wolfei: new insights into syntrophic metabolism and biohydrogen production.
abstract: Syntrophomonas wolfei is a specialist, evolutionarily adapted for syntrophic growth with methanogens and other hydrogen- and/or formate-using microorganisms. This slow-growing anaerobe has three putative ribosome RNA operons, each of which has 16S rRNA and 23S rRNA genes of different length and multiple 5S rRNA genes. The genome also contains 10 RNA-directed, DNA polymerase genes. Genomic analysis shows that S. wolfei relies solely on the reduction of protons, bicarbonate or unsaturated fatty acids to re-oxidize reduced cofactors. Syntrophomonas wolfei lacks the genes needed for aerobic or anaerobic respiration and has an exceptionally limited ability to create ion gradients. An ATP synthase and a pyrophosphatase were the only systems detected capable of creating an ion gradient. Multiple homologues for β-oxidation genes were present even though S. wolfei uses a limited range of fatty acids from four to eight carbons in length.Syntrophomonas wolfei, other syntrophic metabolizers with completed genomic sequences, and thermophilic anaerobes known to produce high molar ratios of hydrogen from glucose have genes to produce H(2) from NADH by an electron bifurcation mechanism. Comparative genomic analysis also suggests that formate production from NADH may involve electron bifurcation. A membrane-bound, iron-sulfur oxidoreductase found in S. wolfei and Syntrophus aciditrophicus may be uniquely involved in reverse electron transport during syntrophic fatty acid metabolism. The genome sequence of S. wolfei reveals several core reactions that may be characteristic of syntrophic fatty acid metabolism and illustrates how biological systems produce hydrogen from thermodynamically difficult reactions.
authors.affiliation: Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Sieber
authors.forename: David R
authors.initials: DR
authors.lastname: Sims
authors.forename: Cliff
authors.initials: C
authors.lastname: Han
authors.forename: Edwin
authors.initials: E
authors.lastname: Kim
authors.forename: Athanasios
authors.initials: A
authors.lastname: Lykidis
authors.forename: Alla L
authors.initials: AL
authors.lastname: Lapidus
authors.forename: Erin
authors.initials: E
authors.lastname: McDonnald
authors.forename: Lars
authors.initials: L
authors.lastname: Rohlin
authors.forename: David E
authors.initials: DE
authors.lastname: Culley
authors.forename: Robert
authors.initials: R
authors.lastname: Gunsalus
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McInerney
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D005561:Formates / Q000378:metabolism; D016680:Genome, Bacterial; D016937:Gram-Positive Endospore-Forming Rods / Q000235:genetics* / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D005561:Formates; D012335:RNA, Ribosomal; C030544:formic acid; D006859:Hydrogen