AN AUTOMATED MONITORING-SYSTEM USING ONLINE ULTRAFILTRATION AND COLUMN LIQUID-CHROMATOGRAPHY FOR ASPERGILLUS-NIGER FERMENTATIONS

An automated system for the monitoring of fermentations of filamentous fungi is described. The system is based on the on-line combination of ultrafiltration, for the removal of cellular and macromolecular mater ial from the fermentation broth, and column liquid chromatography anal ysis of the filtrate. The performance of one hollow-fibre and two plan ar ultrafiltration modules is evaluated. The maximum sampling frequenc y as well as prevention from clogging by mycelium is strongly dependen t on the construction of the module, best results being obtained with a planar membrane and a relatively high flow rate (150 ml/min) of the broth through a single, wide-bore (3mm) flow channel in the module. Th e method is used for the study of metabolic and regulatory processes o f two different Aspergillus niger strains on multiple carbon sources. The selected system can be applied for at least 70 h without any negat ive effect on either the fermentation or the analytical system. Throug h an analysis frequency of once per hour detailed information regardin g consumption and production of nine different compounds could be obta ined.