Optimization of gamma-aminobutyric acid production using sea tangle extract by lactic acid bacterial fermentation

Gamma-aminobutyric acid (GABA) is an important four carbon amino acid known to be involved in the regulation of hypertension, neurotransmission, and stress. Development of functional foods with GABA might impart new health benefits. The present study details about the optimal conditions for the production of GABA using sea tangle (Saccharina japonica) extract (STE). Effect of supplementation of various nutritional factors along with STE on the growth of Lactobacillus brevis BJ-20 and GABA production was investigated. The study suggested that supplementation of nitrogen sources, especially yeast extract at 3% (w/v) with 5 brix STE resulted in significant production of GABA. However, carbohydrates and free amino acids had no significant effect on the GABA production. With optimal conditions, optimal GABA production (76.8 ± 3.4 μg/ml) was detected during 108-120 h with 87% glutamate conversion. Also we observed that the GAD genes related with GABA bioconversion in L. brevis BJ-20 cells were positively regulated in 5 brix STE supplemented with 3% yeast extract. The results of the present study suggested that L. brevis BJ-20 strain can be a resourceful microorganism in developing GABA enriched STE food that can be used as health functional benefits.