L-Glutamate biosensor using a novel l-glutamate oxidase and its application to flow injection analysis system

Abstract

Streptomyces P-106, isolated from soil samples, produced extracellular l-glutamate oxidase in liquid culture. About 10 units enzyme activity per ml medium could be reached after 48–60 h incubation at 28 ° C. A micro-enzyme electrode was prepared by cross linking the purified novel l-glutamate oxidase, produced in our lab, with glutaraldehyde on an aminopropyl-platinized-platinum wire (Φ 0.5 mm). It was used for the determination of l-glutamate in a flow injection analysis system with good performance: accuracy (CV = 0.4%), fast response (< 40 s) and stability (> 30 d). The system showed linear response to the l-glutamate concentration, ranging from 3.0 mg l −1 to 300 mg l −1 (approx. 0.02 mol l −1 to 2.0 mmol l −1). The system was applied to determine the concentration of l-glutamic acid during synthesis. Good correlations were achieved between results obtained with the system and with Warburg method.