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

Abstract

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.

Effect of Low-concentration Furfural on Sulfur Amino Acid Biosynthesis in <i>Saccharomyces cerevisiae</i>

“…However, hydrothermal pretreatment also generates a number of compounds, including furfural, 5-hydroxymethyl furfural (5-HMF), acetic acid, and formic acid 4) , which adversely affect yeast fermentation. High concentrations of furfural have inhibitory effects on yeast growth 5) and fermentation 6) , but the mechanism of inhibition is still under investigation. For example, the addition of furfural is shown to induce the generation of reactive oxygen species in Saccharomyces cerevisiae 7) .…”

Impact of Furfural on Rapid Ethanol Production Using a Membrane Bioreactor

“…Furfural is recognized as one of the most inhibiting substances in the hydrolyzate [5,6]. Consequently, several studies have investigated the effects of furfural on fermentation and yeast growth [7][8][9]. A study made with several different hydrolyzates showed a clear relationship between the sum of furfural and HMF concentrations and the fermentation rate [10].…”

Optimization of dilute acid and alkaline peroxide pretreatment to enhance bioethanol production from wheat straw by co-fermentation

“…Delgenes [31], reported that a concentration of 1 g/L HMF and 0.5 g/L furfural has an inhibitory effect on S. cerevisiae cells. In another study with baker's yeast, it was reported that when 0.9 g/L and 4 g/L furfural found in the media, the ethanol yield decreased by 18% and 79%, respectively [32]. Alkaline peroxide pretreatment is another pretreatment method can be applied to the lignocellulosic biomass.…”