On-line coupling of a miniaturized bioreactor with capillary electrophoresis, via a membrane interface, for monitoring the production of organic acids by microorganisms

Capillary electrophoresis (CE) can be a valuable tool for on-line monitorin g of bioprocesses. Production of organic acids by phosphorus-solubilizing b acteria and fermentation of UHT milk were monitored and controlled by use o f a membrane-interfaced dialysis device and a home-made microsampler for a capillary electrophoresis unit. Use of this specially designed sampling dev ice enabled rapid consecutive injections without interruption of the high v oltage. No additional sample preparation was required. The time resolution of monitoring in this particular work was approximately 2 h, but could be r educed to 2 min. Analytes were detected at low tg mL(-1) levels with a repr oducibility of approximately 10%. To demonstrate the potential of CE in pro cesses of biotechnological interest, results from monitoring phosphate solu bilization by bacteria were submitted to qualitative and quantitative analy sis. Fermentation experiments on UHT milk showed that monitoring of the pro cesses by CE can provide good resolution of complex mixtures, although for more specific, detailed characterization the identification of individual s ubstances is needed.