A deeply branching thermophilic bacterium with an ancient acetyl-CoA pathway dominates a subsurface ecosystem.
A nearly complete genome sequence of Candidatus 'Acetothermum autotrophicum', a presently uncultivated bacterium in candidate division OP1, was revealed by metagenomic analysis of a subsurface thermophilic microbial mat community. Phylogenetic analysis based on the concatenated sequences of proteins common among 367 prokaryotes suggests that Ca. 'A. autotrophicum' is one of the earliest diverging bacterial lineages. It possesses a folate-dependent Wood-Ljungdahl (acetyl-CoA) pathway of CO(2) fixation, is predicted to have an acetogenic lifestyle, and possesses the newly discovered archaeal-autotrophic type of bifunctional fructose 1,6-bisphosphate aldolase/phosphatase. A phylogenetic analysis of the core gene cluster of the acethyl-CoA pathway, shared by acetogens, methanogens, some sulfur- and iron-reducers and dechlorinators, supports the hypothesis that the core gene cluster of Ca. 'A. autotrophicum' is a particularly ancient bacterial pathway. The habitat, physiology and phylogenetic position of Ca. 'A. autotrophicum' support the view that the first bacterial and archaeal lineages were H(2)-dependent acetogens and methanogenes living in hydrothermal environments.
Microbial Genome Research Group, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan. takamih@jamstec.go.jp
Hideto
H
Takami
Hideki
H
Noguchi
Yoshihiro
Y
Takaki
Ikuo
I
Uchiyama
Atsushi
A
Toyoda
Shinro
S
Nishi
Gab-Joo
GJ
Chee
Wataru
W
Arai
Takuro
T
Nunoura
Takehiko
T
Itoh
Masahira
M
Hattori
Ken
K
Takai
D000105:Acetyl Coenzyme A / Q000378:metabolism*; D001419:Bacteria / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D016000:Cluster Analysis; D003062:Codon / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D017753:Ecosystem; D004734:Energy Metabolism; D005798:Genes, Bacterial / Q000235:genetics; D005943:Gluconeogenesis / Q000235:genetics; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D013696:Temperature
D003062:Codon; D004275:DNA, Ribosomal; D000105:Acetyl Coenzyme A