Gama-aminobutyric acid (GABA) is a natural functional amino acid. In present study, we successfully isolated Lactobacillus brevis SIIA11021 which presented a higher GABA-producing ability from Chinese traditional pickled vegetables. A cellular biotransformation process has been taken for the production of GABA, using resting cells of L. brevis SIIA11021 as enzyme systems. Firstly, L. brevis SIIA11021 was incubated anaerobically in 3 % monosodium glutamate (MSG)-containing medium to obtain cells. The L. brevis SIIA11021 cells’ conversion activity of MSG to GABA was induced by MSG. Then these induced resting cells were used to build cell-factory to produce GABA by suspended in 0.2 M disodium hydrogen phosphate-citric acid conversion buffer which contained substrate (MSG) and incubated with appropriate conditions. In this process, ethanol has been added into the conversion buffer and played a key factor to the GABA yield. The effects of pH, temperature and ethanol on GABA-producing have been studied. About 134 mMof GABA has been produced at a conversion rate of 95.7 % under optimal conditions at pH 4.7, 30 oC, supplemented with 1.3 % (v/v) ethanol for 4 h. Besides, a fed-batch fermentation has been taken, using the resting cells biotransformation process in a 3 L beaker fermentor, to produce GABA for 24 h at optimal conditions and the final yield of GABA reached 440 mM. Furthermore, real-time PCR (RT-PCR) analysis displayed that the GAD gene of L. brevis SIIA11021 expression level was induced by MSG.