School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China; College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
J Biosci Bioeng. 2019 Aug;128(2):123-128. doi: 10.1016/j.jbiosc.2019.01.010. Epub 2019 Feb 7.
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 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 GadA 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 GadA cells more valuable for industrial applications.
γ-氨基丁酸（GABA）是制药领域的一种重要化学物质。利用乳酸菌作为生物催化剂将 l-谷氨酸单钠（MSG）转化为 GABA，为生产这种功能性化合物开辟了有趣的前景。在这项工作中，通过过表达在扩展的 pH 范围内具有活性的 C 端截断的 GadA 突变体，构建了 GABA 高产工程菌短乳杆菌 GadA。在与琼脂和κ-卡拉胶进行比较后，选择结冷胶作为最佳固定化载体，并对包埋在这种水凝胶中的短乳杆菌 GadA 细胞的性质进行了研究。发现固定化细胞的最适 pH 和温度分别为 40°C 和 pH 4.4。还观察到细胞的操作稳定性和热稳定性随固定化而提高。在十个连续的反应循环后，在最佳实验条件下，固定化细胞产生的 GABA 总量累积达到 87.56 g/L。总之，提高的稳定性和良好的可用性使固定化的短乳杆菌 GadA 细胞更有价值，可用于工业应用。
