Nuclear Magnetic Resonance Studies of Acetic Acid Inhibition of Rec Zymomonas mobilis ZM4(pZB5)
The fermentation characteristics and effects of lignocellulosic toxic compounds on recombinant Zymomonas mobilis ZM4 (pZB5), which is capable of converting both glucose and xylose to ethanol, and its parental strain, ZM4, were characterized using 13C and 31P nuclear magnetic resonance (NMR) in vivo. From the 31P NMR data, the levels of nucleoside triphosphates (NTP) of ZM(pZB5) using xylose were lower than those of glucose. This can be related to the intrinsically slower assimilation and/or metabolism of xylose compared to glucose and is evidence of a less energized state of ZM4 (pZB5) cells during xylose fermentation. Acetic acid was shown to be strongly inhibitory to ZM4 (pZB5) on xylose medium, with xylose utilization being completely inhibited at pH 5.0 or lower in the presence of 10.9 g/L of sodium acetate. From the 31P NMR results, the addition of sodium acetate caused decreased NTP and sugar phosphates, together with acidification of the cytoplasm. Intracellular deenergization and acidification appear to be the major mechanisms by which acetic acid exerts its toxic effects on this recombinant strain.
Index EntriesRecombinant Zymomonas xylose fermentation 13C nuclear magnetic resonance 31P nuclear magnetic resonance acetic acid inhibition
Unable to display preview. Download preview PDF.
- 2.Rogers, P. L., Lee, K. J., Skotnicki, M. L., and Tribe, D. E. (1982), Adv. Biochem. Eng. 23, 37–84.Google Scholar
- 8.Lohmeier-Vogel, E. M., McIntyre, D. D., Vogel, H. J. (1990), in Physiology of Immobilized Cells, de Bont, J. A. M., Visser, J., Mattiasson, B., and Tramper, J., eds., Elsevier Science, Amsterdam, pp. 661–676.Google Scholar
- 11.Lohmeier-Vogel, E., Hahn-Hägerdal, B., and Vogel, H. J. (1995), Appl. Environ. Microbiol. 61, 1414–1419.Google Scholar
- 13.Barrow, K. D., Collins, J. G., Norton, R. S., Rogers, P. L., and Smith, G. M. (1984), J. Biol. Chem. 259, 5711–5716.Google Scholar
- 16.Ugurbil, K., Shulman, R. G., and Brown, T. R. (1979), in Biological Applications of Magnetic Resonance, Shulman, R. G., ed., Academic, New York, pp. 537–589.Google Scholar
- 17.Maleszka, R. and Schneider, H. (1982), Appl. Environ. Microbiol. 44, 909–912.Google Scholar