Comparative ¹³C‐metabolic flux analysis indicates elevation of ATP regeneration, carbon dioxide, and heat production in industrial Saccharomyces cerevisiae strains

Abstract

Background: Various industrial Saccharomyces cerevisiae strains are used for specific processes, such as sake, wine brewing and bread making. Understanding mechanisms underlying the fermentation performance of these strains would be useful for further engineering of the S. cerevisiae metabolism. However, the relationship between the fermentation performance, intra-cellular metabolic states, and other phenotypic characteristics of industrial yeasts is still unclear. In this study, 13 C-metabolic flux analysis of four diploid yeast strains-laboratory, sake, bread, and wine yeasts-was conducted.Results: While the Crabtree effect was observed for all strains, the metabolic flux level of glycolysis was elevated in bread and sake yeast. Furthermore, increased flux levels of the TCA cycle were commonly observed in the three industrial strains. The specific rates of CO 2 production, net ATP regeneration, and metabolic heat generation estimated from the metabolic flux distribution were two to three times greater than those of the laboratory strain. The elevation in metabolic heat generation was correlated with the tolerance to low-temperature stress. Conclusion:These results indicate that the metabolic flux distribution of sake and bread yeast strains contributes to faster production of ethanol and CO 2 . It is also suggested that the generation of metabolic heat is preferable under the actual industrial fermentation conditions. K E Y W O R D S13 C-based metabolic flux analysis, ATP balance, central carbon metabolism, industrial yeasts, Saccharomyces cerevisiae 1 INTRODUCTION Phenotypic variation among Saccharomyces cerevisiae (budding yeast) strains could provide clues to understanding regulation mechanisms

Improvement of ethanol and 2,3-butanediol production in Saccharomyces cerevisiae by ATP wasting

“…To enhance the alcohol production capacity of S. cerevisiae strains, reducing ATP production or increasing ATP turnover can help reduce ATP waste. We recently performed a metabolic analysis of the laboratory strain BY4947 and three industrial strains with high alcohol fermentation capacities, namely QA23, RedStar, and Kyokai 7, and determined the ATP regeneration and consumption rate based on the total metabolic flux distribution [ 16 ]. Our findings indicated that strains with higher specific growth rates have higher ATP consumption rates and that the rate of ethanol-specific production and the rate of ATP regeneration and consumption are positively correlated [ 16 ].…”

“…We recently performed a metabolic analysis of the laboratory strain BY4947 and three industrial strains with high alcohol fermentation capacities, namely QA23, RedStar, and Kyokai 7, and determined the ATP regeneration and consumption rate based on the total metabolic flux distribution [ 16 ]. Our findings indicated that strains with higher specific growth rates have higher ATP consumption rates and that the rate of ethanol-specific production and the rate of ATP regeneration and consumption are positively correlated [ 16 ]. ATP consumption promotes ADP regeneration via substrate-level phosphorylation in glycolysis, which increases the rate of ethanol production because of overflow metabolism, or the ‘Crabtree effect.’ In addition, the rate of glucose-specific consumption is positively correlated with the rate of ATP regeneration and consumption [ 16 ].…”

“…Our findings indicated that strains with higher specific growth rates have higher ATP consumption rates and that the rate of ethanol-specific production and the rate of ATP regeneration and consumption are positively correlated [ 16 ]. ATP consumption promotes ADP regeneration via substrate-level phosphorylation in glycolysis, which increases the rate of ethanol production because of overflow metabolism, or the ‘Crabtree effect.’ In addition, the rate of glucose-specific consumption is positively correlated with the rate of ATP regeneration and consumption [ 16 ]. Previous studies reported that increased ATP consumption in Escherichia coli and S. cerevisiae enhances substrate uptake and material production rates [ 17 – 20 ].…”

“…Although we have estimated the net ATP regeneration rate using 13 C-based metabolic flux analysis, the purpose of ATP consumption by industrial strains remains unclear. Industrial strains tend to consume more ATP, even at higher growth rates, suggesting that ATP consumption is associated with ethanol production [ 16 ]. Therefore, we hypothesized that artificially consuming ATP could improve alcohol production capacity.…”