title: Genome-guided analysis of physiological and morphological traits of the fermentative acetate oxidizer Thermacetogenium phaeum.
abstract: BACKGROUND
  Thermacetogenium phaeum is a thermophilic strictly anaerobic bacterium oxidizing acetate to CO(2) in syntrophic association with a methanogenic partner. It can also grow in pure culture, e.g., by fermentation of methanol to acetate. The key enzymes of homoacetate fermentation (Wood-Ljungdahl pathway) are used both in acetate oxidation and acetate formation. The obvious reversibility of this pathway in this organism is of specific interest since syntrophic acetate oxidation operates close to the energetic limitations of microbial life.
  
  
  RESULTS
  The genome of Th. phaeum is organized on a single circular chromosome and has a total size of 2,939,057 bp. It comprises 3.215 open reading frames of which 75% could be assigned to a gene function. The G+C content is 53.88 mol%. Many CRISPR sequences were found, indicating heavy phage attack in the past. A complete gene set for a phage was found in the genome, and indications of phage action could also be observed in culture. The genome contained all genes required for CO(2) reduction through the Wood-Ljungdahl pathway, including two formyl tetrahydrofolate ligases, three carbon monoxide dehydrogenases, one formate hydrogenlyase complex, three further formate dehydrogenases, and three further hydrogenases. The bacterium contains a menaquinone MQ-7. No indications of cytochromes or Rnf complexes could be found in the genome.
  
  
  CONCLUSIONS
  The information obtained from the genome sequence indicates that Th. phaeum differs basically from the three homoacetogenic bacteria sequenced so far, i.e., the sodium ion-dependent Acetobacterium woodii, the ethanol-producing Clostridium ljungdahlii, and the cytochrome-containing Moorella thermoacetica. The specific enzyme outfit of Th. phaeum obviously allows ATP formation both in acetate formation and acetate oxidation.
authors.affiliation: Department of Biology, Microbial Ecology, University of Konstanz, Konstanz D-78457, Germany. Dirk.Oehler@uni-konstanz.de
authors.forename: Dirk
authors.initials: D
authors.lastname: Oehler
authors.forename: Anja
authors.initials: A
authors.lastname: Poehlein
authors.forename: Andreas
authors.initials: A
authors.lastname: Leimbach
authors.forename: Nicolai
authors.initials: N
authors.lastname: Müller
authors.forename: Rolf
authors.initials: R
authors.lastname: Daniel
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gottschalk
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schink
mesh_terms: D000085:Acetates / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D001482:Base Composition; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D005285:Fermentation; D016680:Genome, Bacterial / Q000235:genetics*; D023281:Genomics / Q000379:methods*; D016937:Gram-Positive Endospore-Forming Rods / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017422:Sequence Analysis, DNA
chemical_list: D000085:Acetates; D017931:DNA Primers