Continuous conversion of d-xylose to ethanol by immobilized Pachysolen tannophilus

Journal Article · Fri Oct 01 04:00:00 EDT 1982 · Biotechnol. Bioeng.; (United States)

DOI:https://doi.org/10.1002/bit.260241010· OSTI ID:6283241

Slininger, P J; Bothast, R J; Black, L T; McGhee, J E

The yeast Pachysolen tannophilus was entrapped in calcium alginate beads to ferment D-xylose on a continuous basis in the presence of high cell densities. Experimental operating variables included the feed D-xylose concentration, the dilution rate, and the fermentor biomass concentration. Under favorable operating conditions, cultures retained at least 50% of their initial productivity after 26 days of operation. The specific ethanol production rate was dependent on the substrate level in the fermentor, passing through an optimum when the D-xylose concentration was between 28 and 35 g/L. Consequently, reactor productivity increased with dilution rate and feed D-xylose concentration until a maximum was reached. The ethanol content of the effluent always decreased with increasing productivity. Unlike production rate, ethanol yield declined monotonically from 0.35 g/g as the fermentor substrate concentration increased. The yield was 69% of that theoretically possible when the D-xylose concentration was near zero, as opposed to 42% when it was in the range supporting the optimum specific rate of ethanol production. As long as D-xylose was supplied to cells faster than they could consume it, productivity increased with the mass of cells immobilized. The effectiveness factor associated with the calcium alginate beads used in this system was 0.4, indicating that only 40% of the entrapped biomass was effective in converting D-xylose to ethanol because of diffusion limitations. (Refs. 8).

• Research Organization: Northern Regional Research Center, Agricultural Research Service, US Dept of Agriculture, Peoria, IL 61604
• OSTI ID: 6283241
• Journal Information: Biotechnol. Bioeng.; (United States), Journal Name: Biotechnol. Bioeng.; (United States) Vol. 24:10; ISSN BIBIA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALDEHYDES
BIOCONVERSION
BIOREACTORS
CARBOHYDRATES
CONTINUOUS CULTURE
ETHANOL
FERMENTATION
FUNGI
HYDROXY COMPOUNDS
IMMOBILIZED CELLS
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
PENTOSES
PLANTS
PRODUCTION
SACCHARIDES
XYLOSE
YEASTS