<
em>
Clostridium<
/em>
formicoaceticum, a Gram-negative mixotrophic homoacetogen, produces acetic acid as the sole metabolic product from various carbon sources, including fructose, glycerol, formate, and CO<
sub>
2<
/sub>
. Its genome of 4.59-Mbp contains a highly conserved Wood-Ljungdahl pathway gene cluster with the same layout as that in other mixotrophic acetogens, including <
em>
Clostridium aceticum<
/em>
, <
em>
Clostridium carboxidivorans<
/em>
, and <
em>
Clostridium ljungdahlii<
/em>
. For energy conservation, <
em>
C. formicoaceticum<
/em>
does not have all the genes required for the synthesis of cytochrome or quinone used for generating proton gradient in H<
sup>
+<
/sup>
-dependent acetogens such as <
em>
Moorella thermoacetica<
/em>
instead, it has the Rnf system and a Na<
sup>
+<
/sup>
-translocating ATPase similar to the one in <
em>
Acetobacterium<
/em>
woodii. Furthermore its growth in both heterotrophic and autotrophic media were dependent on the sodium concentration. <
em>
C. formicoaceticum<
/em>
has genes encoding acetaldehyde dehydrogenases, alcohol dehydrogenases, and aldehyde oxidoreductases, which could convert acetyl-CoA and acetate to ethanol and butyrate to butanol under excessive reducing equivalent conditions.