The genome of Syntrophus aciditrophicus: Life at the thermodynamic limit of microbial growth

Michael J. McInerney, Lars Rohlin, Housna Mouttaki, Unmi Kim, Rebecca S. Krupp, Luis Rios-Hernandez, Jessica Sieber, Christopher G. Struchtemeyer, Anamitra Bhattacharyya, John W. Campbell, Robert P. Gunsalus

Research output: Contribution to journalArticlepeer-review

206 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)7600-7605
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number18
StatePublished - May 1 2007


  • Anaerobic food chains
  • Fatty acid and benzoate utilization
  • Syntrophic metabolism


Dive into the research topics of 'The genome of Syntrophus aciditrophicus: Life at the thermodynamic limit of microbial growth'. Together they form a unique fingerprint.

Cite this