1. Biosynthesis of γ-aminobutyrate by engineered Lactobacillus brevis cells immobilized in gellan gum gel beads.
- Author
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Lyu CJ, Liu L, Huang J, Zhao WR, Hu S, Mei LH, and Yao SJ
- Subjects
- Fermentation, Hydrogen-Ion Concentration, Levilactobacillus brevis metabolism, Temperature, Cells, Immobilized metabolism, Genetic Engineering, Levilactobacillus brevis cytology, Levilactobacillus brevis genetics, Microspheres, Polysaccharides, Bacterial chemistry, gamma-Aminobutyric Acid biosynthesis
- Abstract
γ-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
ΔC14 was constructed by overexpressing a C-terminally truncated GadA mutant, which is active in expanded pH range. After comparison with agar and κ-carrageenan, gellan gum was selected as the optimal immobilization support, and the properties of L. brevis GadAΔC14 cells encapsulated in this hydrogel were examined. The optimum pH and temperature of immobilized cells were found to be 40°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 GadAΔC14 cells more valuable for industrial applications., (Copyright © 2019 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)- Published
- 2019
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