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Physiological effects of 5-hydroxymethylfurfural on Saccharomyces cerevisiae
M J Taherzadeh1, L Gustafsson, C Niklasson
1Department of Chemical Reaction Engineering, Chalmers University of Technology, Göteborg, Sweden.
Abstract:
The physiological effects of 5-hydroxymethylfurfural (HMF) on Saccharomyces cerevisiae CBS 8066 in the presence and absence of furfural were studied. Experiments were carried out by pulse addition of HMF (2-4 g/l) as well as HMF (2 g/l) together with furfural (2 g/l) to batch cultivations of S. cerevisiae. Synthetic medium with glucose (50 g/l) as carbon and energy source was used. Addition of 4 g/l of HMF caused a decrease (approx. 32%) in the carbon dioxide evolution rate. Furthermore, the HMF was found to be taken up and converted by the yeast with a specific uptake rate of 0.14 (+/-0.03) g/g x h during both aerobic and anaerobic conditions, and the main conversion product was found to be 5-hydroxymethylfurfuryl alcohol. A previously unreported compound was found and characterized by mass spectrometry. It is suggested that the compound is formed from pyruvate and HMF in a reaction possibly catalysed by pyruvate decarboxylase. When HMF was added together with furfural, very little conversion of HMF took place until all of the furfural had been converted. Furthermore, the conversion rates of both furfural and HMF were lower than when added separately and growth was completely inhibited as long as both furfural and HMF were present in the medium.
Insights
5-hydroxymethylfurfural (HMF) impacts Saccharomyces cerevisiae growth and metabolism. Yeast converts HMF to 5-hydroxymethylfurfuryl alcohol, but growth is inhibited when HMF is present with furfural.
Area of Science:
- Microbiology and Biotechnology
- Yeast Physiology
- Biochemical Engineering
Background:
- 5-hydroxymethylfurfural (HMF) is a furanic compound found in various food products and biomass hydrolysates.
- Understanding HMF's physiological effects on industrial yeast strains like Saccharomyces cerevisiae is crucial for optimizing bioprocesses.
- Furfural, another furanic aldehyde, is often present with HMF and known to be toxic to yeast.
Purpose of the Study:
- To investigate the physiological effects of 5-hydroxymethylfurfural (HMF) on Saccharomyces cerevisiae CBS 8066.
- To determine the impact of HMF, alone and in combination with furfural, on yeast growth, metabolism, and conversion pathways.
- To characterize the metabolic products of HMF by S. cerevisiae.
Main Methods:
- Batch cultivations of S. cerevisiae CBS 8066 were performed in synthetic glucose medium.
- Pulse additions of HMF (2-4 g/l) and a mixture of HMF (2 g/l) and furfural (2 g/l) were applied.
- Physiological parameters such as carbon dioxide evolution rate and substrate uptake/conversion rates were monitored.
- Product analysis was conducted using mass spectrometry.
Main Results:
- Addition of 4 g/l HMF decreased the carbon dioxide evolution rate by approximately 32%.
- S. cerevisiae efficiently took up and converted HMF to 5-hydroxymethylfurfuryl alcohol under both aerobic and anaerobic conditions.
- A novel compound, potentially formed from pyruvate and HMF, was identified.
- Co-addition of HMF and furfural led to minimal HMF conversion until furfural depletion, reduced conversion rates for both compounds, and complete growth inhibition.
Conclusions:
- Saccharomyces cerevisiae can metabolize 5-hydroxymethylfurfural (HMF), primarily to 5-hydroxymethylfurfuryl alcohol.
- The presence of furfural significantly inhibits HMF metabolism and yeast growth.
- The findings highlight the challenges of using HMF-containing substrates in yeast fermentation processes due to co-occurring inhibitors like furfural.