Optimization of batch culture conditions for GABA production by Lactobacillus brevis CRL 1942, isolated from quinoa sourdough

gamma-aminobutyric acid (GABA) is a four-carbon amino acid, that acts as a major inhibitory neurotransmitter in the central nervous system. Among nineteen lactic acid bacteria strains, isolated from Andean amaranth (A) and Real Hornillos quinoa (Q(r)) sourdoughs, Lactobacillus brevis CRL 1942 was the most efficient microorganism for the conversion of 53 mM monosodium glutamate (MSG) to GABA, reaching 50 mM after 96 h cultivation. GABA production was enhanced by optimizing culture conditions, such as incubation temperature, time and MSG concentration. A gradual increase of GABA yield was observed at MSG concentrations rising from 0 to 270 mM. In addition, a higher GABA content was observed at 30 degrees C. GABA production occurred in a time-dependent manner, and greatest amount (similar to 255 mM) was yielded after 48 h in cells grown in MRS with 270 mM MSG at 30 degrees C, with a conversion rate of similar to 90%. Cell growth was not affected by MSG addition, implying that the difference in GABA levels could not be attributed to differences in cell numbers. However, addition of glutamate increased viability, indicating a correlation between survival and GABA production. Novel information about LAB with GABA-producing ability is an important breakthrough for the development of health-promoting functional foods. (C) 2015 Elsevier Ltd. All rights reserved.