GABA production by Lactobacillus brevis Qr150, a strain isolated from Andean grains, is influenced by growth media peptide content

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

Egmond aan Zee

Simposio; 11th International Symposium on Lactic Acid Bacteria; 2014

Gamma-aminobutyric acid (GABA), a non-protein amino acid, possesses well-known physiological functions such as neurotransmission, induction of hypotension, diuretic and tranquilizer effects. This compound is synthesized by glutamate decarboxylase (GAD), a pyridoxal 5?-phosphate-dependent enzyme that catalyzes the irreversible α-decarboxylation of L-glutamate to GABA. Several reports have shown the presence of GAD in lactic acid bacteria (LAB), whose decarboxylation has also been coupled with energy synthesis in Lactobacillus. In this study, twenty-two strains isolated from Andean grains and fermented flours (sourdoughs) were tested for their GABA production ability. Among the screened strains, Lactobacillus brevis Qr150,identified by 16S rDNA sequencing, yielded the highest levels of GABA (~300 mM) after 144 h of incubation in MRS broth containing 5% monosodium glutamate (MRSG). GABA production by this microorganism was remarkably higher in cells grown in a peptide-rich medium (MRSG) compared with those found in a chemically defined medium (CDM) in the presence of 5% monosodium glutamate (CDMG). When cells were grown in CDMG supplemented with Casitone, GABA production was considerably enhanced suggesting that GABA synthesis was influenced by the growth media peptide content. These results were confirmed by GAD transcriptional expression. GABA production by L. brevis Qr150 during flour fermentation will contribute to obtain new healthy enriched food products.