Isolation of Baker's Yeast Mutants Defective in γ-aminobutyric Acid Assimilation and Evaluation of Usefulness of these Mutants for Bread Dough Fermentation

Abstract

γ-Aminobutyric acid (GABA) is consumed by yeast during fermentation. To prevent the loss of GABA in fermented food, mutants defective in the assimilation of GABA were isolated from a baker's yeast stain. Each mutant harbored a mutation in the DAL81 gene which encodes a transcription activator that promotes nitrogen source catabolism. Fermentation ability of the mutants was comparable to that of the wild-type strain. Consumption of GABA in fermentation medium by the mutants was significantly suppressed. These mutants could be applied to bread making fermentation in order to maintain GABA at a high level in dough.