Flow injection analysis with immobilized enzymes for process control of pullulan production by fermentation

A flow injection system is described for the parallel determination of pullulan and glucose during a fermentation of the fungus Aureobasidium pullulans. The polysaccharide was hydrolyzed by pullulanase and amyloglucosidase, immobilized to controlled-pore glass (CPG). The glucose produced was oxidized by glucose dehydrogenase and the NADH formed determined photometrically. The pullulan concentration was calculated from the difference to the response obtained for free glucose. The calibration curves for monomer and polymer were both linear between 2 mg dm-3 and 20 mg dm-3. Analysis of one sample for the determination of glucose and pullulan took about 10 min.