| Misoph, MM; Daniel, SL; Drake, HL: Bidirectional usage of ferulate by the acetogen Peptostreptococcus productusU-1: CO | |
| Abstract: The influence of CO2 on the ability of Peptostreptococcus productus U-1 (ATCC 35244) to engage an aromatic acrylate group as an energy-conserving electron acceptor during O-methyl-dependent growth was examined. Ferulate (a methoxylated phenylacrylate), unlike hydroferulate (a methoxylated phenylpropionate), supported growth under CO2-limited conditions and was metabolized according to the following stoichiometry: 1 ferulate ynthesis (CO2 as reductant sink) was minimal. In phase II, acetate synthesis increased, but growth in this phase was much less than that in phase I. In CO2-enriched cultures, distinct phases were not observed, and reductant flow was coupled equally to CO2 and acrylate group reduction. However, in the presence of supplemental CO2, O-methyl and acrylate groups were incompletely metabolized, and molar growth yields were significantly lower compared to CO2-limited conditions. Resting cell studies indicated that the O-demethylase and aromatic acrylate oxidoreductase activities were the result of inducible metabolic potentials. Although these findings demonstrated that P. productus U-1 can engage the aromatic acrylate oxidoreductase system as a sole energy-conserving, electron-accepting process, this acetogen is not able to prevent the simultaneous engagement of the bioenergetically less favorable acetyl-CoA pathway during O-methyl-dependent growth. |
