Medium optimization based on yeast's elemental composition for glutathione production in Saccharomyces cerevisiae

Area of Science:

• Biotechnology
• Microbial Fermentation
• Biochemistry

Background:

• Glutathione (GSH) production in yeast is industrially significant.
• Optimizing Saccharomyces cerevisiae for enhanced GSH is a key research area.

Purpose of the Study:

• Investigate optimal growth rates for GSH production in Saccharomyces cerevisiae Sa-07346.
• Improve fermentation processes for lot-independent biomass and GSH yields.
• Determine the impact of WMIX medium composition and cysteine addition strategies on GSH production.

Main Methods:

• Determined optimal growth rate for GSH production.
• Adjusted fermentation medium based on yeast elemental composition for a chemically defined medium.
• Implemented fed-batch fermentation achieving high cell densities.
• Studied various cysteine addition strategies, including continuous feeding in late-stage fermentation.

Main Results:

• Developed a chemically defined fermentation medium supporting high cell densities in fed-batch cultures.
• Continuous cysteine feeding in late-stage fermentation significantly increased GSH concentration.
• Achieved a maximum GSH concentration of 1459 ± 57 mg/l, a 253% improvement compared to the control (577 mg/l GSH).

Conclusions:

• The developed chemically defined medium and continuous cysteine feeding strategy are effective for high-density yeast fermentation and GSH production.
• This approach has potential for broader application in high cell density yeast fermentation processes.
• Optimized cysteine supply is crucial for maximizing glutathione yields in Saccharomyces cerevisiae.