Diminished respirative growth and enhanced assimilative sugar uptake result in higher specific fermentation rates by the mutant Pichia stipitis FPL-061

Journal Article · Wed Dec 31 04:00:00 EST 1997 · Applied Biochemistry and Biotechnology

DOI:https://doi.org/10.1007/BF02920417· OSTI ID:576215

Sreenath, H K ^[1]; Jeffries, T W ^[1]

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1. Forest Products Lab., Madison, WI (United States)

A mutant strain of Pichia stipitis, FPL-061, was obtained by selecting for growth on L-xylose in the presence of respiratory inhibitors. The specific fermentation rate of FPL-061, was higher than that of the parent, Pichia stipitis CBS 6054, because of its lower cell yield and growth rate and higher specific substrate uptake rate. With a mixture of glucose and xylose, the mutant strain FPL-061 produced 29.4 g ethanol/L with a yield of 0.42 g ethanol/g sugar consumed. By comparison, CBS 6054 produced 25.7 g ethanol/L with a yield of 0.35 g/g. The fermentation was most efficient at an aeration rate of 9.2 mmoles O{sub 2} L{sup -1} h{sup -1}. At high aeration rates (22 mmoles O{sub 2} L{sup -1} h{sup -1}), the mutant cell yield was less than that of the parent. At low aeration rates, (1.1 to 2.5 O{sub 2} L{sup -1} h{sup -1}), cell yields were similar, the ethanol formation rates were low, and xylitol accumulation was observed in both the strains. Both strains respired the ethanol once sugar was exhausted. We infer from the results that the mutant, P. stipitis FPL-061, diverts a larger fraction of its metabolic energy from cell growth into ethanol production. 21 refs., 5 figs.

• OSTI ID: 576215
• Report Number(s): CONF-960539--
• Journal Information: Applied Biochemistry and Biotechnology, Journal Name: Applied Biochemistry and Biotechnology Vol. 63-65; ISSN ABIBDL; ISSN 0273-2289
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
55 BIOLOGY AND MEDICINE
BASIC STUDIES
AERATION
BIOMASS
ETHANOL
FERMENTATION
GLUCOSE
METABOLISM
MUTANTS
UPTAKE
XYLOSE
YIELDS