Acetone butanol fermentation on glucose and xylose. II. Regulation and kinetics in fed-batch cultures
The kinetics in fed-batch cultures of acetone butanol fermentation by Clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. The final conversion yield of sugars into solvents always increases with the sugar feeding rate. At low feeding rates, the sugar concentration in the medium becomes limiting, which results in a slower cellular growth, a slower metabolic transition from an acid to a solvent fermentation and, thus, a higher accumulation of acids. It is only at sufficiently high feeding rates that fed-batch fermentations yield kinetic results comparable to those of batch fermentations. With mixtures of glucose and xylose, because of a maintained low glucose level, both sugars are taken up at the same rate during a first fermentation period. An earlier accumulation of xylose when the fermentation becomes inhibited suggest that xylose utilization is inhibited when the catabolic flux of glucose alone can satisfy the metabolic activity of the cell. Kinetic results with batch and fed-batch fermentations indicate several important features of the regulation of C. acetobutylicum metabolism: an early inhibition by the produced acids; an initiation of solvent formation between 4 and 6 g/L acetic and butyric acid depending on the metabolic activity of the cell; a metabolic transition from acids to solvents production at a rate closely related to the rate of sugar uptake; during solvent production, a reassimilation of acids above a minimal rate of sugar consumption of 0.2 h/sup -1/; a final inhibition of the fermentation at a total butanol and acids concentration of ca. 20 g/L.
- Research Organization:
- Laboratoire des Sciences du Genie Chimique, Nancy Cedex, France
- OSTI ID:
- 6262054
- Journal Information:
- Biotechnol. Bioeng.; (United States), Vol. 28:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ACETONE
YIELDS
BUTANOLS
GLUCOSE
FERMENTATION
XYLOSE
BATCH CULTURE
CHEMICAL FEEDSTOCKS
CLOSTRIDIUM ACETOBUTYLICUM
COMPARATIVE EVALUATIONS
KINETICS
METABOLISM
MIXTURES
SOLVENTS
ALCOHOLS
ALDEHYDES
BACTERIA
BIOCONVERSION
CARBOHYDRATES
CLOSTRIDIUM
DISPERSIONS
HEXOSES
HYDROXY COMPOUNDS
KETONES
METHANOGENIC BACTERIA
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
PENTOSES
SACCHARIDES
090222* - Alcohol Fuels- Preparation from Wastes or Biomass- (1976-1989)
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