Influence of furfural on anaerobic glycolytic kinetics of Saccharomyces cerevisiae in batch culture

• Published in: Biotechnology and bioengineering 1999-02, Vol.62 (4), p.447-454
• Main Authors: Palmqvist, E, Almeida, J.S, Hahn-Hagerdal, B
• Format: Article
• Language: English
• Subjects: acetaldehyde; acetaldehyde inhibition; Anaerobiosis; batch fermentation; Biological and medical sciences; Biotechnology; Carbon - metabolism; Ethanol - metabolism; Fermentation; Fundamental and applied biological sciences. Psychology; Furaldehyde - metabolism; Furaldehyde - pharmacology; Furans - metabolism; Furans - pharmacology; furfural; furfural metabolism; General aspects; Glucose - metabolism; Glycolysis - drug effects; Kinetics; mathematical models; Mathematics in biology. Statistical analysis. Models. Metrology. Data processing in biology (general aspects); mechanistic model; mechanistic models; metabolism; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Models, Biological; NAD - metabolism; Oxidation-Reduction; reaction mechanisms; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/(SICI)1097-0290(19990220)62:4<447::AID-BIT7>3.0.CO;2-0

Furfural was reduced to furfuryl alcohol by Saccaromyces cerevisiae with a yield of 0.97 0.01 mmol/mmol causing a lag phase in cell growth. In the presence of 29 mM, furfural the cell-mass yield on glucose decreased from 11.0 +/- 0.1 mg/mmol (0.06 +/- 0.0006 g/g) in a reference fermentation without furfural to 9.7 +/- 0.07 mg/mmol (0.05 +/- 0.0004 g/g) whereas the ethanol yield on glucose increased from 1.6 +/- 0.03 to 1.7 +/- 0.03 mmol/mmol. No glycerol was excreted during furfural reduction, and the lag phase in acetate production was extended from 1 h in the reference fermentation to 5 h in the presence of furfural. Acetaldehyde and pyruvate were excreted during the furfural reduction phase. Cell growth and cell maintenance were proportional to glucose consumption during the entire fermentation whereas the cell-mass yield on ATP produced was low during furfural reduction. These observations indicate that furfural addition to a batch culture decreased cell replication without inhibiting cell activity (designated as replicative inactivation). The absence of glycerol production during furfural reduction suggests that furfural acted as an alternative redox sink oxidizing excess NADH formed in biosynthesis. A mechanistic mathematical model was developed that described accurately the fermentation in the absence and presence of furfural. The model was based on the assumptions that: (i) furfural reduction to furfuryl alcohol by NADH-dependent dehydrogenases had a higher priority than reduction of dihydroxyacetone phosphate to glycerol; and (ii) furfural caused inactivation of cell replication. The effect of furfural on cell replication is discussed in relation to acetaldehyde formation. Inactivation of cell replication was modeled by considering two populations within the cell culture, both metabolically active, but only one replicating. The kinetic description was developed as a tool to estimate transient fluxes of carbon, NADH/NAD+ and ATP/ADP.