Metabolic flux analysis of Saccharomyces cerevisiae during redox potential–controlled very high‐gravity ethanol fermentation

Abstract

A previously published genome‐scale metabolic model namely iFF708 was modified to depict the metabolic flux distribution within Saccharomyces cerevisiae grown under a redox potential–controlled very high‐gravity condition. The following modifications were made: electron transport chain (ETC) and oxidative phosphorylation, proton gradient and ATP transportation, and malate–aspartate shuttle. With these modifications, this model could describe the experimental data collected from the above‐mentioned ethanol fermentation. As a result, the simulation unveiled that the P/O ratio is critical under microaerobic conditions and the malate–aspartate shuttle is inactivated due to the shortage of electron transport across mitochondria. In other words, the limited supply of oxygen suppresses the functionality of oxidative phosphorylation, tricarboxylic acid (TCA) cycle, and ETC. In terms of the glycolytic pathway, fluxes coming from glucose‐6‐phosphate and pyruvate nodes are insensitive to the changes of fermentation redox potential. As the initial glucose concentration is greater than 250 g/L, the interactive effect between the initial glucose concentration and redox potential level becomes noticeable.

Enhanced multi-stress tolerance and glucose utilization of Saccharomyces cerevisiae by overexpression of the SNF1 gene and varied beta isoform of Snf1 dominates in stresses

“…Author details 1 College of Food Science and Engineering, Hainan University, Haikou 570228, People's Republic of China. 2 College of Science, Hainan University, Haikou 570228, People's Republic of China.…”

“…Saccharomyces cerevisiae is a typical eukaryotic model organism and widely used in fermentation industries. High-sugar fermentation is widely applied in various fermentation industry because of its high productivity, efficient equipment utilization, low energy consumption and production cost [1,2]. However, S. cerevisiae cells inevitably suffer from high sugar osmotic pressure at the initial stage of fermentation.…”

Monitoring Site-Specific Fermentation Outcomes via Oxidation Reduction Potential and UV-Vis Spectroscopy to Characterize “Hidden” Parameters of Pinot Noir Wine Fermentations

“…By 12–24 h post-inoculation, the ORP declined to roughly −100 mV for all fermentations. This change in ORP is indicative of yeast metabolic activity, including the uptake of oxygen and excretion of reductive metabolites ( Figure 3 C) [ 40 ]. For SNC1 and OR1 ~12 h after inoculation, a nutrient addition was made to adjust the YAN, so these fermentations had a total of 250 mg/L ( Figure 3 C).…”

Real-time and on-line monitoring of ethanol fermentation process by viable cell sensor and electronic nose

“…Especially, the real-time acquisition of key parameters can provide a basis for on-line dynamic regulation. A variety of process regulation strategies have been developed to achieve efficient fermentation of ethanol by Saccharomyces cerevisiae , including alleviation of high concentration of substrates and product inhibition (Zhang et al 2015 ; Ji et al 2012 ), engineering for high-performance strains (Wu et al 2020 ; Naghshbandi et al 2019 ; Liu et al 2019 ) and optimization of environmental conditions (Zhang et al 2020 ; Liu et al 2013 ). However, at present, the common control of industrial ethanol fermentation process is based on artificial experience and on-line detection parameters mainly involved in operating parameters, while key indexes including biomass, substrates, product and by-products, which are of great importance, were basically measured by off-line methods (Dekker et al 2017 ).…”