1(College of Bioengineering, Tianjin University of Science and Technology, Tianjin 300457,China) 2(Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin 300457,China)
Abstract: To study the effects of acetic acid bacteria on alcohol fermentation and ester-alcohol metabolism of yeast, Acetobacter pasteurium, a common strain found in liquor production, was mixed with high ester-producing Saccharomyces cerevisiae. While keeping the inoculation amount of high ester-producing Saccharomyces cerevisiae unchanged, different amount of acetic acid bacteria suspension and acetic acid bacteria fermentation liquid were added to the sorghum juice medium. The results showed that the acetic acid bacteria suspension had little effect on alcohol fermentation and ester-alcohol metabolism. However, with increasing in the acetic acid concentration (0~6 g/L), the amount of acetate and higher alcohols decreased gradually, and alcohol fermentation remained unchanged. Specifically, the acetate and higher alcohols decreased by up to 60% and 50%, respectively. When the acetic acid concentration reached 8 g/L, the alcohol fermentation and ester-alcohol metabolism were severely inhibited, and ethanol production dropped by 85%. In addition, at the initial acetic acid concentration of 6 g/L, 394 genes were up-regulated and 282 genes were down-regulated in the high ester-producing Saccharomyces cerevisiae. These genes were mainly encoded for cell membrane components and physiological function, antibiotic synthesis, secondary metabolites synthesis, carbon metabolism, TCA cycle, amino acids synthesis and other metabolic pathways.
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2020, Vol. 46 
