Fermentation of pentoses and hexoses from spent sulfite pulping liquor: potential for genetic engineering applications
The bulk of the work described here relates to the computer simulation of biomass fermentations in general and to the application of these simulation programs to an existing large-scale fermentation process. The xylose isomerase enzyme from Escherichia coli was purified and its amino acid and gene-sequences determined. The gene was inserted into two yeast strains; the gene produced a protein that resembled xylose isomerase but had no enzymatic activity. In contrast to xylose, hexoses from biomass wastes are routinely fermented to ethanol. The Georgia-Pacific plant in Bellingham, Washington for fermentation of spent liquor from calcium sulfite pulping has an annal capacity of six million gallons of ethanol. A computer model describing this continuous fermentation has been developed. The model is used to test the likely or potential effect of altered fermentation kinetic parameters and plant operating parameters on steady-state process concentrations. The Monod model for cell growth and ethanol production is used (this kinetic model is described in Chapter Four), with appropriate modifications to account for multisubstrate fermentation. Parameters for the Monod kinetic equations are determined using a numerical maximum-likelihood technique to fit experimental data. Steady-state concentrations are calculated by simultaneous solution of the nonlinear differential equations that describe the mass balances for fermentation reactions in each tank. The potential effect of pentose fermentation upon the industrial process is calculated using various estimates of the pentose fermentation behavior that might be achievable in this process, including estimates developed from the fermentation of xylulose.
- Research Organization:
- Washington Univ., Seattle (USA)
- OSTI ID:
- 5482484
- Country of Publication:
- United States
- Language:
- English
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ALCOHOLS
BIOCONVERSION
CARBOHYDRATES
COMPUTERIZED SIMULATION
ENZYMES
ETHANOL
ETHANOL PLANTS
FERMENTATION
FUNGI
GENETIC ENGINEERING
HEXOSES
HYDROXY COMPOUNDS
INDUSTRIAL PLANTS
INDUSTRIAL WASTES
LIQUID WASTES
MASS BALANCE
MATHEMATICAL MODELS
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
PENTOSES
PLANTS
SACCHARIDES
SIMULATION
SPENT LIQUORS
WASTES
YEASTS