Polyol production by culture of methanol-utilizing yeast

Area of Science:

• Biotechnology
• Microbiology
• Biochemistry

Background:

• Methanol-utilizing yeasts are known for their ability to produce polyols.
• Optimizing fermentation conditions is crucial for maximizing polyol yields.

Purpose of the Study:

• To investigate polyol production from sugars by four methanol-utilizing yeasts.
• To identify optimal conditions for xylitol production by Hansenula polymorpha.

Main Methods:

• Cultivation of Candida boidinii, Hansenula polymorpha, Hansenula ofunaensis, and Pichia pinus in a methanol medium.
• Optimization of pH, nitrogen source, and substrate concentration for xylitol production.
• Fermentation using D-xylose and glycerol as substrates.

Main Results:

• Hansenula polymorpha demonstrated superior xylitol production compared to other tested yeasts.
• Optimal production conditions included pH 8, 5 g (dry)/l cultured cells, 2.5 g/l urea, 1% (v/v) methanol, and 1 g/l MgSO4.7H2O.
• A yield of 57 g/l xylitol was achieved from 110 g/l D-xylose in 3 days. The highest xylitol yield (58 g/l; 0.62 g/g) was obtained from 125 g/l D-xylose and 5% (w/v) glycerol in 4 days.

Conclusions:

• Hansenula polymorpha is a promising yeast for xylitol production.
• Glycerol can be a viable alternative substrate to methanol for enhanced xylitol yield.
• Further optimization of fermentation parameters can improve polyol production efficiency.