Industrial on-line monitoring of penicillin V, glucose and ethanol using a split-flow modified thermal biosensor

Abstract

Penicillin V, glucose and ethanol were monitored in 0.5 and 2.5 m 3 bioreactors using an enzyme thermistor, modified for split-flow analysis. Penicillin V was also monitored in a 160 m 3 bioreactor. The samples were split immediately before similtaneously entering the enzyme column and an identical reference column, (without enzyme). By using a reference column the non-specific heat arising from mixing and solvation effects caused by high salt and metabolite concentrations in the fermentation broth can be eliminated. Immobolized β-lactamase in the enzyme column was used to monitor three consecutive fermentations, but the penicillin V values were 10% higher than the values obtained by off-line liquid chromatographic(LC) analysis of the same samples. Another enzyme was therefore used with the same set-up. After purification from a broth supernatant, penicillin V acylase was used for on-line monitoring of penicillin production in a 160 m 3 bioreactor. The concentrations of penicilloic acid, p-hydroxypenicillin V and penicillin V were determined by off-line LC. The sum of these concentrations matched the on-line biosensor values very well. Glucose was monitored from the start in a Saccharomyces fermentation but after 5 h the analysis was switched to ethanol monitoring. It took 60 min to switch from a glucose oxidase column to a column with alcohol oxidase and obtain the first on-line ethanol value.