According to a new research study initiated by the researchers of the Nara Institute of Science and Technology and the Nara Prefecture Institute of Industrial Development have reported to discover a mutant strain of traditional Japanese alcoholic beverage sake yeast producing high levels of ornithine. Ornithine is an amino acid and aids in reducing fatigue and enhances sleep quality. Moreover, the researchers also revealed that this mutant strain of sake yeast yields amino acid ornithine more than 10 times the amount, in comparison to parent yeast strain. Masataka Ohashi, first author, stated, “We wanted to obtain sake yeast strains with improved ethanol tolerance. During sake fermentation, the yeast is exposed to high concentrations of ethanol, which impedes yeast cell growth, viability and fermentation. Increased ethanol tolerance in sake yeast strains could improve ethanol production and reduce fermentation time.†Initially, in order to obtain ethanol-tolerant yeast strains, researchers isolated mutants that accrued proline, which lessens toxicity of ethanol by utilizing a conventional mutagenesis deprived of any genetic modification. Moreover, researchers also piloted whole genome sequencing analysis, and conducted brewing tests with sake yeast strains. Later, researchers identified and examined a new mutation in a gene that encodes a variant of N-acetyl glutamate kinase boosting intracellular ornithine level. Furthermore, researchers isolated those non-genetically modified yeasts, which generated over 10 times the amount of ornithine, in comparison to parent strain. Researchers concluded from the outcomes of the study this study can further aid in the development of enhanced yeast strains for production of high levels of ornithine, and the strain obtained in this study could be readily used in wine, sake, and beer brewing.
