C. Matthies et al., FUMARATE DISSIMILATION AND DIFFERENTIAL REDUCTANT FLOW BY CLOSTRIDIUM-FORMICOACETICUM AND CLOSTRIDIUM-ACETICUM, Archives of microbiology, 160(4), 1993, pp. 273-278
Methanol and the O-methyl group of vanillate did not support the growt
h of Clostridium formicoaceticum in defined medium under CO2-limited c
onditions, however, they were growth supportive when fumarate was prov
ided concomitantly. Fumarate alone was not growth supportive under the
se conditions. Fumarate reduction (dissimilation) to succinate was the
predominant electron-accepting, energy-conserving process for methano
l-derived reductant under CO2-limited conditions. However, when both r
eductant sinks, i.e., fumarate and CO2, were available, reductant was
redirected towards CO2 in defined medium. In contrast, in undefined me
dium with both reductant sinks available, C. formicoaceticum simultane
ously engaged fumarate dismutation and the concomitant usage of CO2 an
d fumarate as reductant sinks. With Clostridium aceticum, fumarate als
o substituted for CO2, and H-2 became growth supportive under CO2-limi
ted conditions. Fumarate dissimilation was the predominant electron-ac
cepting process under CO2-limited conditions; however, when both reduc
tant sinks were available, H-2-derived reductant was routed towards CO
2, indicating that acetogenesis was the preferred electron-accepting p
rocess when reductant flow originated from H-2. Collectively, these fi
ndings indicate that fumarate dissimilation, not dismutation, is selec
tively used under certain conditions and that such usage of fumarate i
s subject to complex regulation.