The pH-dependent energetic uncoupling of Zymomonas by acetic acid

Journal Article · · Applied Biochemistry and Biotechnology; (United States)

DOI:https://doi.org/10.1007/BF02941818· OSTI ID:7086331

Lawford, H G; Rousseau, J D ^[1]

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1. Univ. of Toronto, Ontario (Canada)

PH-dependent energetic uncoupling of Zymomonas 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 a 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 [Delta]pH and the concentration 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 an 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.

• OSTI ID: 7086331
• Journal Information: Applied Biochemistry and Biotechnology; (United States), Journal Name: Applied Biochemistry and Biotechnology; (United States) Vol. 45-46; ISSN ABIBDL; ISSN 0273-2289
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090900* -- Biomass Fuels-- Processing-- (1990-)
550700 -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
ALCOHOL FUELS
BACTERIA
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
ETHANOL FUELS
FUELS
MICROORGANISMS
SYNTHESIS
SYNTHETIC FUELS
ZYMOMONAS MOBILIS