Enterococcus avium from a traditional Chinese liquor fermentation system with the potential for the de novo synthesis of GABA

γ-Aminobutyric acid (GABA) is a prevalent nonprotein amino acid with diverse physiological functions, attracting considerable interest in the food industry. However, current GABA-producing strains require glutamate as a substrate for synthesis. Probiotics capable of de novo GABA synthesis using sugars without glutamate are crucial for developing novel foods. This study employed a pH indicator method to selectively screen for GABA-producing bacteria. Nineteen strains with fermentation liquid pH greater than 5 were obtained, all demonstrated the ability to synthesize GABA from Daqu . Among these strains, Enterococcus (E.) avium GL1 stood out for its high GABA production capacity, reaching 9.8 g/L when utilizing glucose for de novo GABA synthesis without monosodium glutamate (MSG). E. avium GL1 exhibited robust viability in challenging environments, maintaining stability in simulated gastric and intestinal fluids. As a potentially probiotic strain, E. avium GL1 achieved remarkable GABA production of 206.84 g/L with a production efficiency of 2.87 g/L/h, facilitated by automatic pH control during fermentation through continuous addition of glucose and MSG addition. This exceptional result represents the highest GABA production reported for E. avium , highlighting its significant potential for the development of innovative functional foods.