IMPROVEMENT OF AN E. COLI FERMENTATION BY ON-LINE MONITORING OF GLUCOSE AND TOTAL AMINO ACIDS USING A FIBRE OPTIC FIA-SYSTEM

Abstract

Anew methodfor the determination of glucose and total amino acids using a fibre optic biosensor in combination with a flow injection system (FIA) is presented. The biosensors are basedonfibre optic oxygen optrodes which measure the oxygen consumptionvia dynamic quenching ofthe fluorescence ofan indicator by molecular oxygen. Enzymecartridgeswith immobilized glucose oxidase (EC 1.1.3.4.) fromA. niger and amino acid oxidase (EC 1.4.3.2) from Crotalus adamanteus were integrated into flow through chamberscovering oxygen optrodes. The FIA-system wasusedto dilute and buffer the on-line sterilefiltered samples taken automatically from the fermenter by-pass loop. This detection set-up was successfully used to improvethecell density of E. coli fermentations by controlled medium supply. The fermentations were carried out for the production of recombinant protein.