Biotransformation of Sodium L-Glutamate to gamma-Aminobutyric Acid by L. Brevis TCCC13007 with Two Glutamate Decarboxylase Genes

Due to the important physiological functions of GABA, various methods used to produce it. Biotransformation by microorganism cells is a more promising method than others. Among the GABA-producing lactic acid bacteria, one strain with high producing capacity was isolated from Chinese naturally pickled vegetable. The strain is identified as Lactobacillus brevis, and named as L.brevis TCCC13007 based on its physiological and biochemical characteristics and homology of 16S rDNA. In this study, two gad genes were cloned by PCR using the genomic DNA of L.brevis TCCC13007 as template. The deduced amino acid sequence of one gad gene showed 100%, 98.5% and 95.9% identity of L.brevis ATCC367, L. brevis BH2 and L. brevis OPK-3, respectively. The other showed 99.8% and 99.4% identity of L.brevis ATCC367 and L.brevis IFO12005 respectively. According to the properties of GAD, the optimal biotransformation condition was investigated. Under the optimal condition, L.brevis TCCC13007 synthesised GABA at a concentration of 39 g·L^-1.