A mathematical model for yeast respiro-fermentative physiology

Area of Science:

• Microbiology
• Biochemical Engineering
• Systems Biology

Background:

• Yeast respiro-fermentative physiology is complex, involving multiple glucose uptake and assimilation pathways.
• Existing models often rely on simplified assumptions like critical switches or maximum respiratory capacity.

Purpose of the Study:

• To develop a mechanistic model for yeast respiro-fermentative physiology.
• To explain the relationship between substrate concentration, glucose uptake, and product formation.
• To provide a generalizable model for heterotrophic microorganism metabolism.

Main Methods:

• Developed a mechanistic model incorporating multiple glucose carriers and assimilation pathways.
• Analyzed the mechanistic response of these pathways to varying substrate concentrations.
• Estimated model parameters by fitting data from existing literature.

Main Results:

• The model demonstrates how high-affinity/low-rate and low-affinity/high-rate glucose carriers dominate at low and high substrate concentrations, respectively.
• Lower assimilation efficiency and biomass yield are linked to high uptake rates at high substrate concentrations.
• Product formation is associated with high uptake rate pathways, explaining observed substrate-product relationships.

Conclusions:

• The model successfully explains respiro-fermentative physiology based on carrier kinetics and substrate concentration.
• It offers a more nuanced understanding than models relying on critical switches.
• The model's principles are applicable to the general metabolism of heterotrophic microorganisms.