Cloning and Expression of a Full-Length Glutamate Decarboxylase Gene from Lactobacillus brevis BH2

A bacterium (BH2) that was found to produce a large amount of γ-aminobutyric acid (GABA) was isolated from Kimchi, a traditional fermented food in Korea. Phylogenetic analysis based on the 16S rDNA sequence and biochemical studies indicated that BH2 belonged to the genus Lactobacillus brevis. Under controlled conditions in MRS broth (Difco) with 5% monosodium glutamate, this strain produced GABA at a concentration of 194 mM with a 73% GABA conversion rate after 48 h. A full-length glutamate decarboxylase (gad) gene was cloned by the rapid amplification of cDNA ends (RACE) PCR.