Screening of gamma‐aminobutyric acid‐producing lactic acid bacteria and the characteristic of glutamate decarboxylase from Levilactobacillus brevis F109‐MD3 isolated from kimchi.

Aims: This study aimed to screen the γ‐aminobutyric acid (GABA)‐producing lactic acid bacteria (LAB) from kimchi, and investigate the glutamate decarboxylase (GAD) activity of the highest GABA‐producing strain. Methods and Results: Seven strains of LAB were screened from kimchi with GABA‐producing activity. Strain Levilactobacillus brevis F109‐MD3 showed the highest GABA‐producing ability. It produced GABA at a concentration of 520 mmol l−1 with a 97.4% GABA conversion rate in MRS broth containing 10% monosodium glutamate for 72 h. The addition of pyridoxal 5'‐phosphate had no significant effect on the GAD activity of L. brevis F109‐MD3. The optimal pH range of GAD was 3.0–5.0 and the optimal temperature was 65°C. The D value of GAD at 50, 60 and 70°C was 7143, 971 and 124 min respectively and Z value was 11.36°C. Conclusions: Seven strains isolated from kimchi, especially F109‐MD3, showed high GABA‐production ability even in the high concentrations of MSG at 7.5% and 10%. The GAD activity showed an effective broad pH range and higher optimal temperature. Significance and Impact of the Study: These seven strains could be potentially useful for food‐grade GABA production and the development of healthy foods. [ABSTRACT FROM AUTHOR]