Influences of adding media additives on synthesis of gamma‐aminobutyric acid in fermentation of defatted rice bran extract with lactic acid bacteria

Summary Gamma‐aminobutyric acid (GABA), a main inhibitory neurotransmitter in brain, is a nonproteinogenic amino acid. The production of GABA from rice bran by lactic acid bacteria ( Lactobacillus brevis ) is an approach for maximising the potential of agricultural byproduct and reducing production cost. The use of media additives enhances the efficiency of GABA production, but their effects on cells and biomass in fermentation must be assessed to determine the appropriate concentration and efficiency. The influences of CaCl 2 (0–1.5% w/v), Tween 80 (0–0.9% w/v), MnSO 4 (0–0.6% w/v) and Pyridoxine hydrochloride (0–90 ppm) at different concentrations on GABA production by defatted rice bran extract fermentation using Lb. brevis VTCC‐B397 were evaluated. The changes in cell density, GABA content, reducing sugar content and pH value were observed. Consequently, the impact of media additive compounds on growth, development and GABA synthesis of Lb. brevis was demonstrated. Results showed that CaCl 2 , MnSO 4 and Tween 80 positively affected GABA production from defatted rice bran extract by fermentation method.