Screening of Acetate-Tolerant Yeast and Its Effect on Controlling Bacterial Contamination During Ethanol Production from Sugarcane Molasses

Growth and ethanol fermentation ability of the acetate-tolerant yeastSaccharomyces cerevisiaeKU 002-3 strain were investigated in acetate-addition medium. Under simulated industrial conditions, acetate did not affect on sugar consumption and ethanol production of KU 002-3. Moreover, KU 002-3 strain demonstrated a higher capability for ethanol production than other commercial strains. Co-fermentation was conducted withLactobacillus fermentumIFRPD 2021, the major contaminating bacteria, during the ethanol production at 0.8% (v/v) acetate (130 mM of the undissociated form of acetate). Under these conditions, growth ofL. fermentumIFRPD 2021 was inhibited but the growth and ethanol production ability ofS. cerevisiaeKU 002-3 strain were not significantly affected. Data indicated the possibility of producing ethanol under high acetate accumulation and reducingLactobacillussp. in molasses medium or acetate-containing condition. Producing ethanol under high acetate accumulation and lower the contamination ofLactobacillussp. in a molasses medium can be useful at industrial scale to produce ethanol withS. cerevisiaeKU 002-3 under non-sterilized conditions.

Automated summary

The study showed that acetate did not affect the sugar consumption and ethanol production of the acetate-tolerant yeast strain KU 002-3, and it exhibited a higher capability for ethanol production compared to other commercial strains. Co-fermentation with Lactobacillus fermentumIFRPD 2021 at 0.8% acetate inhibited the growth of the bacteria but did not significantly affect the growth and ethanol production ability of S. cerevisiae KU 002-3. The data indicated the possibility of producing ethanol under high acetate accumulation and reducing contamination of Lactobacillus sp. in molasses medium.