Acetogenesis and acetogenic bacteria

Acetogens reduce CO₂ to acetate via the acetyl-CoA pathway and have been classically thought of as obligately anaerobic bacteria.  Nearly 100 acetogenic species from 20 different genera have been isolated to date.  These isolates are able to use very diverse electron donors and acceptors, and it is likely that the in situ activities of acetogens are not restricted to acetogenesis.  Acetogens constitute a phylogenetically diverse bacteriological group and are important in very diverse habitats, including habitats not generally regarded as suitable for acetogens.  Although the ecological impact of acetogens is determined by the in situ manifestation of their physiological potentials, assessing their in situ activities is difficult due to their physiological and phylogenetic diversities.  Research on acetogenic bacteria is focused on: (i) metabolic and habitat diversities, (ii) regulation, (iii) phylogeny and molecular ecology, (iv) symbiotic relationships, and (v) the capacity of acetogens to cope with oxic in situ conditions.