M. Misoph et al., BIDIRECTIONAL USAGE OF FERULATE BY THE ACETOGEN PEPTOSTREPTOCOCCUS-PRODUCTUS-U-1 - CO2 AND AROMATIC ACRYLATE GROUPS AS COMPETING ELECTRON ACCEPTORS, Microbiology, 142, 1996, pp. 1983-1988
The influence of CO2 on the ability of Peptostreptococcus) productus U
-1 (ATCC 35244) to use an aromatic acrylate group as an energy-conserv
ing electron acceptor during O-methyl-dependent growth was examined. F
erulate (a methoxylated phenylacrylate), unlike hydroferulate (a metho
xylated phenylpropionate), supported growth under CO2-limited conditio
ns. Two phases occurred during ferulate utilization in CO2-limited cul
tures. In phase I (maximum growth), O-methyl-derived reductant was cou
pled mainly to acrylate group reduction, and acetate synthesis (CO2 as
reductant sink) was minimal. In phase II, acetate synthesis increased
, but cell yields in this phase were much less than in phase I. In CO2
-enriched cultures, distinct phases were not observed; reductant was c
oupled equally to CO2 and acrylate group reduction. Under CO2-enriched
conditions, O-methyl and acrylate groups were incompletely metabolize
d, and molar growth yields were significantly lower compared to CO2-li
mited conditions. Resting cell studies indicated that O-demethylase an
d aromatic acrylate oxidoreductase activities were induced by ferulate
. These findings demonstrated that P. productus U-1 can use the aromat
ic acrylate oxidoreductase system as a sole, energy-conserving, electr
on-accepting process, but is not able to prevent the simultaneous use
of the bioenergetically less favourable acetyl-CoA pathway during O-me
thyl-dependent growth.