Physiological adaptations of anaerobic bacteria to low pH: metabolic control of proton motive force in Sarcina ventriculi
Detailed physiological studies were done to compare the influence of environmental pH and fermentation end product formation on metabolism, growth, and proton motive force in Sarcina ventriculi. The kinetics of end product formation during glucose fermentation in unbuffered batch cultures shifted from hydrogen-acetate production to ethanol production as the medium pH dropped from 7.0 to 3.3. At a constant pH of 3.0, the production of acetate ceased when the accumulation of acetate in the medium reached 40 mmol/liter. At a constant pH of 7.0, acetate production continued throughout the entire growth time course. The in vivo hydrogenase activity was much higher in cells grown at pH 7.0 than at pH 3.0. The magnitude of the proton motive force increased in relation to a decrease of the medium pH from 7.5 to 3.0. When the organism was grown at pH 3.0, the cytoplasmic pH was 4.25 and the organism was unable to exclude acetic acid or butyric acid from the cytoplasm. Addition of acetic acid, but not hydrogen or ethanol, inhibited growth and resulted in proton motive force dissipation and the accumulation of acetic acid in the cytoplasm. The results indicate that S. ventriculi is an acidophile that can continue to produce ethanol at low cytoplasmic pH values. Both the ability to shift to ethanol production and the ability to continue to ferment glucose while cytoplasmic pH values are low adapt S. ventriculi for growth at low pH.
- Research Organization:
- Univ. of Wisconsin, Madison
- DOE Contract Number:
- FG02-85ER13376
- OSTI ID:
- 6430156
- Journal Information:
- J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 169:5; ISSN JOBAA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
090222* -- Alcohol Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
ACETATES
ALCOHOLS
ALDEHYDES
BACTERIA
BATCH CULTURE
BIOCONVERSION
BIOLOGICAL ADAPTATION
CARBOHYDRATES
CARBOXYLIC ACID SALTS
ENZYME ACTIVITY
ENZYMES
ETHANOL
FERMENTATION
GLUCOSE
GROWTH
HEXOSES
HYDROGENASES
HYDROXY COMPOUNDS
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PH VALUE
SACCHARIDES
YIELDS