Aims To assess the ability of human intestinally derived strains of Lactobacillus and Bifidobacterium to produce ?-aminobutyric acid (GABA). Methods and Results Strains of Lactobacillus and Bifidobacterium were grown in medium containing monosodium glutamate (MSG). Growth of the bacteria and conversion of MSG to GABA were measured. Of 91 intestinally derived bacteria assessed, one Lactobacillus strain and four strains of Bifidobacterium produced GABA. Lactobacillus brevis DPC6108 was the most efficient of the strains tested, converting up to 100% of MSG to GABA. The ability of the cultured intestinal strains to produce GABA was investigated using a simple pH-controlled anaerobic faeces-based fermentation, supplemented with 30 similar to mg similar to ml-1 MSG. The addition of Lact.similar to brevis DPC6108 to a faeces-based fermentation significantly increased the GABA concentration (P similar to

Keywords:GABA;intestinal microbiology;lactic acid bacteria;probiotics