Applied Biochemistry and Biotechnology

, Volume 45, Issue 1, pp 437–448 | Cite as

The pH-dependent energetic uncoupling ofZymomonas by acetic acid

Scientific note
  • Hugh G. Lawford
  • Joyce D. Rousseau
Session 2 Applied Biological Research


pH-dependent energetic uncoupling ofZymomonas by acetic acid occurs by virtue of the permeability of the plasma membrane to the undissociated form of acetic acid (HAc) and the acidification of the cytoplasm resulting from the uptake of HAc and the consequential diversion of energy away from biosynthetic processes (growth) in order to maintain constant intracellular pH. Energetic uncoupling is manifested by an increase in specific productivity. The degree of uncoupling caused by HAc depends on a rather complex interaction between several different variables including membrane permeability, the transmembrane δpH and the concentraiton of undissociated form of acetic acid in the medium. Within the pH range of 5.0–5.5, maximal energic uncoupling is produced by 30–38 mM HAc. For practical purposes, in terms of the concentration of acetic acid, this corresponds to about 5 and 15 g/L at pH 5.0 and 5.5, respectively. Assuming any upper limit concentration of acetic acid in hydrolysate fermentation media of about 12 g/L, inhibition of Z.mobilis in terms of both ethanol yield and productivity is avoided by controlling the pH in the range of 5.5–6.0.

Index Entries

Zymomonas acetic acid fuel ethanol energetic uncoupling specific productivity 



undissociated acetic acid


specific growth rate (h−1)


growth yield co-efficient (g dry wt cells/g glucose)


product yield (g ethanol/g glucose)


average volumetric productivity (g ethanol/L/h)


specific productivity (g ethanol/g cell/h).


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Wright, J. D. (1988),Chem. Eng. Progress 84, 62–68.Google Scholar
  2. 2.
    Wyman, C. E. and Hinman, N. D. (1990),Appl. Biochem. Biotechnol. 24/25, 735–753.CrossRefGoogle Scholar
  3. 3.
    Hinman, N. D., Wright, J. D., Hoagland, W., and Wyman, C. E. (1989),Appl. Biochem. Biotechnol. 20/21, 391–401.CrossRefGoogle Scholar
  4. 4.
    Keim, C. R. (1983),Enzyme Microbiol. Technol. 5, 103–114.CrossRefGoogle Scholar
  5. 5.
    Busche, R., Scott, C. D., Davidson, B. H., and Lynd, L. R. (1992),Appl. Biochem. Biotechnol. 34/35, 395–417.CrossRefGoogle Scholar
  6. 6.
    Maiorella, B. L., Blanch, H. W., and Wilke, C. R. (1984),Bioeng. Biotechnol. 26, 1003–1025.CrossRefGoogle Scholar
  7. 7.
    Ohta, K., Supanwong, K., and Hayashida, S. (1981),J. Ferment. Technol. 59, 435–439.Google Scholar
  8. 8.
    Lawford, H. G. (1988),Appl. Biochem. Biotechnol. 17, 203–219.CrossRefGoogle Scholar
  9. 9.
    Lawford, H. G. (1988), Proc. VIII Int’l Symp. on Alcohol Fuels, Pub. by NEDO, Tokyo, pp. 21–27.Google Scholar
  10. 10.
    Lawford, H. G. and Ruggiero, A. (1990), inBioenergy, Proc. 7th Cdn. Bioenergy R&D Seminar, Hogan, E., ed., NRC Canada, pp. 401–408.Google Scholar
  11. 11.
    Rogers, P. L., Lee, K. J., Skotnicki, M. L., and Tribe, D. E. (1982),Adv. Biochem. Eng. 23, 37–84.Google Scholar
  12. 12.
    Doelle, H. W., Kirk, L., Crittenden, R., Toh, H., and Doelle, M. B. (1993),CRC Rev. Biotechnol. 13(1), 57–98.CrossRefGoogle Scholar
  13. 13.
    Rodriguez, E. and Callieri, D. A. S. (1986),Biotechnol. Letts 8, 745–748.CrossRefGoogle Scholar
  14. 14.
    Doelle, M. B., Greenfield, P. F., and Doelle, H. W. (1990),Proc. Biochem. 25(5), 151–156.Google Scholar
  15. 15.
    Beavan, M., Zawadzki, B., Droniuk, R., Fein, J., and Lawford, H. G. (1989),Appl. Biochem. Biotechnol. 20/21, 319–326.CrossRefGoogle Scholar
  16. 16.
    Bringer, S., Sahm, H., and Swyzen, W. (1984),Biotechnol. Bioeng. Symp. 14, 311–319.Google Scholar
  17. 17.
    Lee, G. M., Kim, C. H., Lee, K. J., Zainal Abidin Mohd. Yusof, Han, M. H., and Rhee, S. K. (1986),J. Ferment Technol. 64, 293–297.CrossRefGoogle Scholar
  18. 18.
    Parekh, S. R., Parekh, R. S., and Wayman, M., (1989),Proc. Biochem. 24, 88–91.Google Scholar
  19. 19.
    Freese, E., Sheu, C. W., and Galliers, E. (1973),Nature 241, 321.CrossRefGoogle Scholar
  20. 20.
    Lynd, L. R. (1990),Appl. Biochem. Biotechnol. 24/25, 695–719.CrossRefGoogle Scholar
  21. 21.
    Grethlein, H. E. (1985),Bio/Technolgy 3, 155–160.CrossRefGoogle Scholar
  22. 22.
    Lawford, H. G. and Rousseau, J. D. (1993), inEnergy from Biomass & Wastes XVI, Klass, D. L., ed., Institute of Gas Technology, Chicago, IL, pp. 559–597.Google Scholar
  23. 23.
    Lawford, H. G. and Rousseau, J. D. (1993),Appl. Biochem. Biotechnol. 39/40, 301–322.CrossRefGoogle Scholar
  24. 24.
    Lawford, H. G. and Rousseau, J. D. (1992),Appl. Biochem. Biotechnol. 34/35, 205–216.CrossRefGoogle Scholar
  25. 25.
    Lawford, H. G. and Rousseau, J. D. (1993),Appl. Biochem. Biotechnol. 39/40, 687–699.CrossRefGoogle Scholar
  26. 26.
    Nicholls, D. G. (1982), Bioenergetics—anintroduction to the chemiosmotic theory, Academic, Toronto, pp. 56–58.Google Scholar
  27. 27.
    Swings, J. and De Ley, J. (1977),Bacteriol. Rev. 41, 1–46.Google Scholar
  28. 28.
    Lawford, H. G. and Ruggiero, A. (1990),Biotechnol. Appl. Biochem. 12, 206–211.Google Scholar
  29. 29.
    Pampulha, M. E. and Louriero, V. (1989),Biotechnol. Letts. 11, 269–274.CrossRefGoogle Scholar
  30. 30.
    Mitchell, P. (1973),J. Bioenergetics 4, 63–91.CrossRefGoogle Scholar
  31. 31.
    Pankova, L. M., Shvinka, J. E., and Beker, M. J. (1988),Appl. Microbiol. Biotechnol. 28, 583–588.CrossRefGoogle Scholar
  32. 32.
    Pirt, S. J. (1975),Principles of Microbe and Cell Cultivation, Blackwell, London, UK, pp. 66–68.Google Scholar
  33. 33.
    Maiorella, B. L., Blanch, H. W., and Wilke, C. R. (1983),Biotechnol. Bioeng. 25, 103–121.CrossRefGoogle Scholar
  34. 34.
    Vega, J. L., Claussen, E. C., and Gaddy, J. L. (1987),Biotechnol. Bioeng. 29, 429–435.CrossRefGoogle Scholar
  35. 35.
    Lavers, B. H., Pang, P., MacKenzie, C. R., Lawford, G. R., Pik, J., and Lawford, H. G. (1981), inAdvances in Biotechnology, Moo-Young, M. and Robinson, C. W., eds., vol. II, Pergamon, Toronto, pp. 195–204.Google Scholar

Copyright information

© Humana Press Inc. 1994

Authors and Affiliations

  • Hugh G. Lawford
    • 1
  • Joyce D. Rousseau
    • 1
  1. 1.Department of BiochemistryUniversity of TorontoTorontoCanada

Personalised recommendations