Abstract: The abilities of six Zygosaccharomyces mellis strains to metabolize carbon sources, nitrogen sources and vitamins were investigated. It turned out that Z. mellis 6-7431 had stronger ability of utilizing nutrients than the other strains. Then the physiological response of Z. mellis 6-7431 to high-glucose stress was characterized. Its morphology and reproduction pattern under high-glucose stress were observed using scanning electron microscopy (SEM). The concentrations of metabolites such as glycerol, trehalose and malic acid were also determined. Results showed that Z. mellis 6-7431 exhibited a normal budding reproduction and the concentrations of these metabolites were elevated in the glucose concentration range of 300-500 g/L relative to a 100 g/L concentration. When glucose concentration increased from 550 to 700 g/L, Z. mellis 6-7431 started to form spores gradually, and the concentrations of these metabolites varied. At a high glucose concentration of 750 g/L, strain 6-7431 was dehydrated and its morphology became wizened. All the metabolic activities of this strain were inhibited, and the alcoholic concentration was only 0.6% in the fermented broth. These findings facilitated our understanding of the physiological response to high-glucose exposure and glucose-tolerant mechanism of Z. mellis 6-7431.

Key words: Zygosaccharomyces mellis, high-glucose stress, reproductive mode, stress metabolites