title: The genome of Syntrophus aciditrophicus: life at the thermodynamic limit of microbial growth.
abstract: Biochemically, the syntrophic bacteria constitute the missing link in our understanding of anaerobic flow of carbon in the biosphere. The completed genome sequence of Syntrophus aciditrophicus SB, a model fatty acid- and aromatic acid-degrading syntrophic bacterium, provides a glimpse of the composition and architecture of the electron transfer and energy-transducing systems needed to exist on marginal energy economies of a syntrophic lifestyle. The genome contains 3,179,300 base pairs and 3,169 genes where 1,618 genes were assigned putative functions. Metabolic reconstruction of the gene inventory revealed that most biosynthetic pathways of a typical Gram-negative microbe were present. A distinctive feature of syntrophic metabolism is the need for reverse electron transport; the presence of a unique Rnf-type ion-translocating electron transfer complex, menaquinone, and membrane-bound Fe-S proteins with associated heterodisulfide reductase domains suggests mechanisms to accomplish this task. Previously undescribed approaches to degrade fatty and aromatic acids, including multiple AMP-forming CoA ligases and acyl-CoA synthetases seem to be present as ways to form and dissipate ion gradients by using a sodium-based energy strategy. Thus, S. aciditrophicus, although nutritionally self-sufficient, seems to be a syntrophic specialist with limited fermentative and respiratory metabolism. Genomic analysis confirms the S. aciditrophicus metabolic and regulatory commitment to a nonconventional mode of life compared with our prevailing understanding of microbiology.
authors: Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA.
authors: Michael J
authors: MJ
authors: McInerney
authors: Lars
authors: L
authors: Rohlin
authors: Housna
authors: H
authors: Mouttaki
authors: UnMi
authors: U
authors: Kim
authors: Rebecca S
authors: RS
authors: Krupp
authors: Luis
authors: L
authors: Rios-Hernandez
authors: Jessica
authors: J
authors: Sieber
authors: Christopher G
authors: CG
authors: Struchtemeyer
authors: Anamitra
authors: A
authors: Bhattacharyya
authors: John W
authors: JW
authors: Campbell
authors: Robert P
authors: RP
authors: Gunsalus
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D020564:Deltaproteobacteria / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism; D004583:Electrons; D016680:Genome, Bacterial / Q000235:genetics*; D050296:Microbial Viability; D008969:Molecular Sequence Data; D005810:Multigene Family; D010766:Phosphorylation; D015398:Signal Transduction; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D000255:Adenosine Triphosphate