Ethanol production by thermophilic bacteria: fermentation of cellulosic substrates by cocultures of Clostridium thermocellum and Clostridium thermohydrosulfuricum
The fermentation of various saccharides derived from cellulosic biomass to ethanol was examined in mono- and cocultures of Clostridium thermocellum strain LQRI and C. thermohydrosulfuricum strain 39E. C. thermohydrosulfuricum fermented glucose, cellobiose, and xylose, but not cellulose or xylan, and yielded ethanol/acetate ratios of >7.0 C. thermocellum fermented a variety of cellulosic substrates, glucose, and cellobiose, but not xylan or xylose, and yielded ethanol/acetate ratios of approx. 1.0. A stable coculture that contained nearly equal numbers of C. thermocellum and C. thermohydrosulfuricum was established that fermented a variety of cellulosic substrates, and the ethanol yield observed was twofold higher than in C. thermocellum monoculture fermentations. The metabolic basis for the enhanced fermentation effectiveness of the coculture on Solka Floc cellulose included: the ability of C. thermocellum cellulase to hydrolyze ..cap alpha..-cellulose and hemicellulose; the enhanced utilization of mono- and disaccharides by C. thermohydrosulfuricum; increased cellulose consumption; threefold increase in the ethanol production rate; and twofold decrease in the acetate production rate.
- Research Organization:
- Univ. of Wisconsin, Madison
- OSTI ID:
- 6298673
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 41:6; ISSN AEMID
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550700* -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALDEHYDES
BACTERIA
BIOCONVERSION
CARBOHYDRATES
CELLOBIOSE
CELLULOSE
CLOSTRIDIUM
DISACCHARIDES
ETHANOL
FERMENTATION
GLUCOSE
HEMICELLULOSE
HEXOSES
HYDROXY COMPOUNDS
MICROORGANISMS
MONOSACCHARIDES
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
PENTOSES
POLYSACCHARIDES
SACCHARIDES
XYLANS
XYLOSE