Mass Production of Yeast Spores from Compressed Yeast

Saccharomyces yeast spores are more resistant to drying and storage than vegetative cells. For the mass production of yeast spores, compressed yeast was directly inoculated into a sporulation medium (SM). The effects of inoculum size and the addition of rice wine cake (RWC) into SM on the sporulation were examined using flasks. With 1% inoculum of compressed yeast, 1.45×10 8 /ml of asci was obtained. The addition of 0.5% RWC into SM improved the cell growth and spore yield, and the number of asci formed was 2.31×10 8 /ml. The effects of culture temperature, temperature-shift, and concentrations of inoculum, potassium acetate, and RWC on the sporulation were also evaluated using a jar fermentor. The optimum temperature for spore formation was 22°C where the number of asci formed was 2.46×10 8 /ml. The shift of culture temperature from initial 30°C for 1 day to 22C for 3 days increased the number of asci formed to 2.96×10 8 / ml. The use of 2% (w/v) inoculum of compressed yeast, 2% potassium acetate, and 1% (w/v) RWC in SM with the shift of culture temperature of initial 30C to 22C resulted in 90% sporulation ratio and formation of 6.15×10 8 asci/ml.