Production of gamma-aminobutyric acid by lactic acid bacteria isolated from quinoa and amaranth flours

VILLEGAS, J.M.; HEBERT, E.M.; SAVOY DE GIORI, G.

Simposio; IV International Symposium on Lactic Acid Bacteria: Food, Health and Applications.; 2013

Gamma-aminobutyric acid (GABA), a four-carbon non-protein amino acid, acts as a major inhibitory neurotransmitter in the central nervous system, and has several physiological functions such as neurotransmission, induction of hypotensive effects, diuretic effects, treatment of epilepsy and tranquilizer effects. GABA is synthesized by glutamate decarboxylase, a pyridoxal 5-phossphate dependent enzyme that catalyzes the irreversible decarboxylation of L-glutamate to GABA. Taking into account these physiological functions and considering that lactic acid bacteria (LAB) are used as starter cultures in the manufacturing processes of many fermented products, several functional foods containing GABA could be manufactured. The aim of this study was to analyze the GABAproducing ability of twenty-two LAB strains isolated from Andean amaranth (A) and Real Hornillos quinoa (Qr) flours sourdoughs. Only three GABA-producing strains (Qr150, A174 and A206) were detected by thin layer chromatography. GABA concentration was determined by HPLC when the selected strains were grown in MRS broth containing 1% L-monosodium glutamate (MSG) at 30ºC for 96 h. The strain Qr150, isolated from quinoa real flour, produced the highest amount of GABA (50 mM). This microorganism was identified as Lactobacillus brevis based on 16S rDNA sequence analysis. The GABA production was further improved by optimizing the culture conditions (incubation temperature and glutamate concentration). Cells grown in MRS with 5% MSG yielded the greatest amount of GABA (254 mM), showing a conversion rate of 86% from the supplied MSG. Taking into account that the production of bacterial GABA is safe and offers the possibility to produce new health fermented products enriched in this amino acid, further studies on the fermentation process are needed before its industrial application.