Gamma-aminobutyric acid (GABA) is a non-protein amino acid with several physiological functions, including hypotensive and tranquilizing effects. In this study, thin-layer chromatography was used to select 18 strains of lactic acid bacteria, out of 218 strains isolated from dairy products, for high GABA productivity. GABA production by the 18 strains was measured using HPLC, with strain 1056 showing the highest GABA productivity (6.95 mg/mL). This strain was identified as Lactobacillus brevis by morphological, physiological and genetic analyses. Lb. brevis 1056 produced GABA when it was cultured in media adjusted to an initial pH of 4.0-8.0, rather than 3.0. GABA production by strain 1056 increased with increasing amounts of glutamate (substrate) added to the medium (pH 5.0). It was also shown that GABA production by strain 1056 was faster than the other strains. These results suggest that Lb. brevis 1056 is a useful starter for GABA-rich functional foods. Lastly, as a model functional food, fermented chicken sauce was prepared using Lb. brevis 1056, and sufficient amounts (1.51 mg/mL) of GABA were produced in the sauce.
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