RAPID DETERMINATION OF GLUTAMIC ACID BASED ON IMMOBILIZED ESCHERICHIA COLI AND A QUADRUPOLE MASS SPECTROMETER

Abstract

Large quantities of glutamic acid are produced by the fermentation process so that rapid determination of glutamic acid is important for the control of the fermentation. Previously, we reported a microbial sensor consisting of immobilized Escherichia coli containing glutamte decarboxylase activity and a carbon dioxide gas-sensing electrode(1). The sensor has a major disadvantage of slow speed, 10 samples per hour, due to slow response of the gas-sensing electrode. We require more rapid sensors to deal with many samples from the fermentation laboratories. In stead of the gas-sensing electrode, a quadrupole mass spectrometer was employed to measure carbon dioxide gas produced from glutamic acid by the immobilized E.coli(2). The method has very high speed, more than 100 samples per hour, and has been applied to the assay of glutamic acid in the fermentation broths: