Glycerol production by microbial fermentation: a review

Area of Science:

• Biotechnology
• Industrial Microbiology
• Biochemical Engineering

Background:

• Microbial glycerol production, known for 150 years, declined due to low yields and purification challenges compared to petrochemical synthesis.
• Increasing propylene costs and glycerol's value as a chemical feedstock are reviving interest in fermentation-based glycerol production.
• Traditional methods to enhance microbial glycerol synthesis include acetaldehyde-bisulfite complexation, high pH cultivation, and osmotolerant yeast utilization.

Purpose of the Study:

• To review recent advancements in microbial glycerol production, particularly focusing on osmotolerant yeasts and commercial-scale applications.
• To highlight improvements in glycerol yield, productivity, and downstream processing techniques.
• To discuss the potential of metabolic engineering for developing novel glycerol-overproducing microorganisms.

Main Methods:

• Isolation and characterization of novel osmotolerant yeast strains for high-yield glycerol production.
• Optimization of aerobic fermentation processes to maximize glycerol concentration, yield, and productivity.
• Development of efficient downstream processing, such as carrier distillation, for glycerol recovery.

Main Results:

• Novel osmotolerant yeast strains achieved up to 130 g/L glycerol with 63% yield and 32 g/(L day) productivity.
• Commercial-scale aerobic fermentation reached 58% yield, 30 g/(L day) productivity, and 110-120 g/L concentration.
• A carrier distillation technique demonstrated over 90% glycerol recovery efficiency.

Conclusions:

• Significant progress has been made in commercial-scale microbial glycerol production using osmotolerant yeasts.
• Optimized fermentation and advanced purification methods enhance the economic viability of bio-based glycerol.
• Further opportunities exist for improving glycerol production through metabolic engineering and a deeper understanding of yeast metabolism.