Effect of oxygenation on xylose fermentation by Pichia stipitis

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Applied and Environmental Microbiology; (USA)

OSTI ID:6122079

Skoog, K; Hahn-Haegerdal, B ^[1]

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1. Applied Microbiology, Lund (Sweden)

The effect of oxygen limitation on xylose fermentation by Pichia stipitis (CBS 6054) was investigated in continuous culture. The maximum specific ethanol productivity (0.20 g of ethanol g dry weight{sup {minus}1} h{sup {minus}1}) and ethanol yield (0.48 g/g) was reached at an oxygen transfer rate below 1 mmol/liter per h. In the studied range of oxygenation, the xylose reductase (EC 1.1.1.21) and xylitol dehydrogenase (EC 1.1.1.9) activities were constant as well as the ratio between the NADPH and NADH activities of xylose reductase. No xylitol production was found. The pyruvate decarboxylase (EC 4.1.1.1) activity increased and the malate dehydrogenase (EC 1.1.1.37) activity decreased with decreasing oxygenation. With decreasing oxygenation, the intracellular intermediary metabolites sedoheptulose 7-phosphate, glucose 6-phosphate, fructose 1,6-diphosphate, and malate accumulated slightly while pyruvate decreased. The ratio of the xylose uptake rate under aerobic conditions, in contrast to that under anaerobic assay conditions, increased with increasing oxygenation in the culture. The results are discussed in relation to the energy level in the cell, the redox balance, and the mitochondrial function.

• OSTI ID: 6122079
• Journal Information: Applied and Environmental Microbiology; (USA), Vol. 56:11; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
ETHANOL
BIOSYNTHESIS
OXYGEN
BIOLOGICAL EFFECTS
XYLOSE
FERMENTATION
YEASTS
PRODUCTIVITY
ENZYME ACTIVITY
METABOLITES
ALCOHOLS
ALDEHYDES
BIOCONVERSION
CARBOHYDRATES
ELEMENTS
EUMYCOTA
FUNGI
HYDROXY COMPOUNDS
MICROORGANISMS
MONOSACCHARIDES
NONMETALS
ORGANIC COMPOUNDS
PENTOSES
PLANTS
SACCHARIDES
SYNTHESIS
090900* - Biomass Fuels- Processing- (1990-)