Isolation and Partial Characterization of 2-Deoxy-D-glucose Resistant Saccharomyces cerevisiae Strain from Fruits Harvested in Yamagata, Japan

Aims: The study aimed to isolate and characterize 2-deoxy-D-glucose (2-DG) resistant Saccharomyces cerevisiae from fruits to establish distinctive bread making technology using wild-type yeasts in the future.

Study Design: The research was conducted experimentally.

Place and Duration of Study: Yamagata University, Yamagata, Japan, from April 2015 to March 2019.

Methodology: Wild-type yeasts with 2-DG resistance were isolated using the following experiments: 1. Separation by yeast nitrogen base-maltose plate medium, 2. Carbon dioxide (CO2) and ethanol production tests, 3. Leavening ability tests using bread doughs, 4. Sequence analysis. The identified yeast strain was used for freezing and drying torelance tests. Moreover, it tried to improve drying tolerance of yeasts.

Results: Yeasts were separated from twenty varieties of five fruits species. Among them, a yeast strain (YTPR1) isolated from pear Redbartllet fruits was identified as S. cerevisiae. YTPR1 possessed high fermentation ability and freezing tolerance, however, CO2 and ethanol production decreased after lyophilization of yeasts. In contrast, the cultivation with trehalose, glycerol, and L-glutamic acid at low concentration enhanced the fermentation ability of YTPR1.

Conclusion: Yeast YTPR1 isolated from pear Redbartllet fruits utilized maltose as well as glucose, fructose, and sucrose. To improve drying tolerance of yeast YTPR1, it was useful to incubate with 6% trehalose, 0.1-2.0% glycerol and 1.0% L-glutamic acid.