Redox cofactor metabolism in Saccharomyces cerevisiae and its impact on the production of alcoholic fermentation end-products

• Published in: Food research international 2023-01, Vol.163, p.112276-112276, Article 112276
• Main Authors: Duncan, James D., Setati, Mathabatha E., Divol, Benoit
• Format: Article
• Language: English
• Subjects: Alcoholic fermentation; Fermentation; NAD - metabolism; NAD(H); NADP - metabolism; NADP(H); Oxidation-Reduction; Redox balance; Redox cofactors; Saccharomyces cerevisiae; Saccharomyces cerevisiae - metabolism; Wine
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2022.112276

[Display omitted] •Intracellular redox balance was monitored in S. cerevisiae during alcoholic fermentation.•NADP(H) level and ratio were stable over time in all strains.•NAD(H) concentration was found to decrease over time in a strain-dependent manner.•NAD+/NADH ratio was also found to evolve in a strain-dependent manner.•Redox cofactor management translated into different levels of metabolic end-products. The alcoholic fermentation of organic carbon sources by Saccharomyces cerevisiae produces many by-products, with the most abundant originating from central carbon metabolism. The production of these metabolites involves redox reactions and largely depends on the maintenance of redox homeostasis. Despite the metabolic pathways being mostly conserved across strains of S. cerevisiae, their production of various amounts of metabolic products suggests that their intracellular concentration of redox cofactors and/or redox balance differ. This study explored the redox status dynamics and NAD(H) and NADP(H) cofactor ratios throughout alcoholic fermentation in four S. cerevisiae strains that exhibit different carbon metabolic fluxes. This study focussed on the molecular end-products of fermentation, redox cofactor ratios and the impact thereof on redox homeostasis. Strain-dependent differences were identified in the redox cofactor levels, with NADP(H) ratios and levels remaining stable while NAD(H) levels decreased drastically as the fermentation progressed. Changes in the NAD+/NADH ratio were also observed. Total levels of NAD(H) decreased drastically as the fermentation progressed despite the cells remaining viable until the end of fermentation. NAD+ was found to be favoured initially while NADH was favoured towards the end of the fermentation. The change in the NAD+/NADH redox cofactor ratio during fermentation was linked with the production of end-products. The findings in this study could steer further research in the selection of S. cerevisiae wine strains for desirable aroma contributions based on their intracellular redox balance management.