Enhanced production of γ-aminobutyric acid (GABA) using Lactobacillus plantarum EJ2014 with simple medium composition

γ-Aminobutyric acid (GABA) is an amino acid not present in proteins. GABA participates in a variety of physiological functions and has received significant attention in the medical and food industries. In this study, GABA production was investigated using Lactobacillus plantarum. We designed a synthetic medium consisting of the simplest medium components such as yeast extract (nitrogen source), glucose (carbon source), and monosodium l-glutamate (MSG; substrate for GABA) and optimized their proportions to efficiently produce GABA. As a result, 19.8 g/L GABA was obtained under an optimal synthetic medium composition of 100 g/L yeast extract, 10 g/L glucose, and 2.25% MSG, which is the highest among previous studies using L. plantarum. Interestingly, 159.7% of theoretical maximum yield based on initial MSG content was obtained since yeast extract acts as a secondary source of substrate. By proper optimization with the simplest medium using L. plantarum, it can produce a high titer of GABA as well as might help various functional foods containing GABA to develop.