A Study on the Efficient Preparation of α-Ketoglutarate with L-Glutamate Oxidase.

Alpha-ketoglutaric acid (α-KG), as an intermediate product of the tricarboxylic acid cycle, plays a crucial role in peptide and amino acid synthesis. In order to reduce costs and improve efficiency in the oxidative production of α-ketoglutaric acid, this study successfully synthesized and expressed L-glutamate oxidase (LGOX) from R111 and catalase (KatG) from H736. Two immobilization methods and the conditions for one-step whole-cell catalysis of α-ketoglutaric acid were investigated. α-Ketoglutaric acid has broad applications in the pharmaceutical, food, and chemical industries. The specific research results are as follows: (1) By fusing the sfGFP tag, L-glutamate oxidase (LGOX r) and catalase (KatG) were successfully anchored to the outer membrane of cells, achieving one-step whole-cell catalysis of α-ketoglutaric acid with a conversion efficiency of up to 75%. (2) Through the co-immobilization of LGOX and KatG, optimization of the preparation parameters of immobilized cells, and exploration of the immobilization method using @ZIF-8, immobilized cells with conversion rates of over 60% were obtained even after 10 cycles of reuse. Under the optimal conditions, the production rate of α-ketoglutaric acid reached 96.7% in a 12 h reaction, which is 1.1 times that of @SA and 1.29 times that of free cells.