gamma-Aminobutyrate (GABA) is an important chemical in pharmaceutical field. The use of lactic acid bacteria as biocatalysts for the conversion of L-monosodium glutamate (MSG) into GABA opens interesting perspectives for the production of this functional compound. In this work, an engineered GABA high-producing strain Lactobacillus brevis GadA(Delta C14) was constructed by overexpressing a C-terminally truncated GadA mutant, which is active in expanded pH range. After comparison with agar and kappa-carrageenan, gellan gum was selected as the optimal immobilization support, and the properties of L. brevis GadA(Delta C14) cells encapsulated in this hydrogel were examined. The optimum pH and temperature of immobilized cells were found to be 40 degrees C and pH 4.4, respectively. It was also observed that operational and thermal stabilities of the cells were increased with immobilization. After ten consecutive reaction cycles, the total amounts of GABA produced by the immobilized cells summed up to 87.56 g/L under the optimum experimental conditions. Taken together, the improved stability and good usability make the immobilized L brevis GadA(Delta C14) cells more valuable for industrial applications. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.