标题：Establishment of an Efficient Fermentation System of Gamma-Aminobutyric Acid by a Lactic Acid Bacterium, Enterococcus avium G-15, Isolated from Carrot Leaves
摘要：In the present study, we successfully isolated a carrot leaf-derived lactic acid bacterium that produces gamma-aminobutyric acid (GABA) from monosodium L -glutamate ( L -MSG) at a hyper conversion rate. The GABA-producing bacterium, identified as Enterococcus ( E. ) avium G-15, produced 115.7±6.4 g/l GABA at a conversion rate of 86.0±5.0% from the added L -MSG under the optimum culture condition by a continuous L -MSG feeding method using a jar-fermentor, suggesting that the bacterium displays a great potential ability for the commercial-level fermentation production of GABA. Using the reverse transcription polymerase chain reaction (RT-PCR) method, we analyzed the expression of genes for the GABA transporter and glutamate decarboxylase, designated gadT and gadG , respectively, which were cloned from the E. avium G-15 chromosome. Both genes were expressed even without the added L -MSG, but their expression was enhanced by the addition of L -MSG.
