A continuous method for monitoring and controlling fermentations: Using an automated HPLC system

Abstract

Fermentation processes still lack rapid, reliable, and quantitative methodology for the real time analysis of substrates and products. Real time data on fermentation components lend itself not only to monitoring complex mixtures, but also to simple control on demand features. Some of the latest method employed involve the use of immobilized enzyme probes to monitor a substrate such as glucose, or a product such as ethanol in an ultrafiltered stream. Mass spectrometers have been used to analyze fermentation off-gases for volatile components such as O/sub 2/, CO/sub 2/, and ethanol. Each of the enzyme sensor methods is substrate specific and a complex fermentation requires the monitoring of several soluble components. Recently, Ivie proposed using an automated HPLC system to monitor and control an ethanol fermentation. An HPLC system has the advantage of being able to discriminate between several different components, usually in less than 15 min, depending on proper column selection. However, samples must be periodically removed from the fermenter, filtered and manually placed in the HPLC injector system for analysis. The system described here uses an automated, computer controlled HPLC system. The unit was fitted with a continuous flow-through sample vial for the on-line analysis of fermentation broths. Resultsmore » of monitoring a simple yeast fermentatin of glucose to ethanol are reported.« less