A biosensor based on oriented immobilization of an engineered L-glutamate oxidase on a screen-printed microchip for detection of L-glutamate in fermentation processes

This paper describes an amperometric biosensor utilizing an engineered L-glutamate oxidase for glutamate monitoring in microbial fermentation processes. We designed a general immobilization strategy that utilized a chitin-binding domain (ChBD-tag) as a biotether to further immobilize L-glutamate oxidase (GLOX) in an oriented manner on a screen-printed Prussian blue nanocube microchip (PB/SPC) with the biopolymer chitosan. The improved L-glutamate biosensor exhibited an enhanced sensitivity of 53.4 µA L mmol⁻¹ cm⁻² and a linear range from 25 µmol/L to 300 µmol/L with a detection limit of 9 µmol/L, and retained 95 % of its initial activity after two weeks of usage. In addition, the as-prepared biosensor was applied for real-time monitoring of food ingredient L-glutamate concentration during the fermentation process, which was in good agreement with that of high-performance liquid chromatography (HPLC). Above all, the L-glutamate biosensor prepared by this method had high analytical performance, and could fully realize real-time and high-efficiency monitoring in glutamate fermentation.