Abstract: A biosensor for the determination of glucose, fructose, gluconolactone and sorbitol is described. The sensor used either permeabilized Zymomonas mobilis or glucose - fructose oxidoreductase isolated from Z. mobilis. The sensing element was confined to a small measuring chamber fitted with a membrane. This was incorporated into a FIA system. The principle of the system was that the NADP(H) cofactor molecule, which is confined in a protein complex, would be oxidized or reduced during enzymatic reactions, and could be made to undergo fluorescence by excitation at 360 nm (measurement at 450 nm). Using this sensor, changes in fluoresence intensity were related to substrate concentration and the range of sensitivity found to be from 0.001 to 100 g L-1 of analyte. The system was shown to be capable of monitoring bioprocesses by using it to determine the relevant analytes in samples from a Pseudomonas pseudoflava cultivation.

Abstract: Glucose, maltose, sucrose, lactose, xylose, sorbose, galactose, fructose and gluconolactone were analyzed by means of immobilized pyranose oxidase as well as by the combination of immobilized glucose oxidase with immobilized glycoamylase, invertase, mutarotase, maltase (α-glucosidase) and glucose isomerase by flow injection analysis (FIA). For the simultaneous analysis of glucose and other sugars three different flow injection configurations were applied and compared. The average error of prediction of the analyzes were better than 3% in model media and better than 6% in yeast extract containing media.