Penicillin fermentation in a 200-liter tower fermentor using cells confined to microbeads

The scale-up of the penicillin fermentation through cell confinement in a 200-L tower fermentor is described. P. chrysogenum spores were adsorbed into Celite microbeads having diameters greater than 180 microns. Fed-batch fermentations were performed using both free and confined cells. Cell growth and penicillin concentrations were measured during the fermentation. In addition, the oxygen transfer rate, the aeration rate, and the level of dissolved oxygen were also measured. Significant improvement in the mass transfer coefficient was found when the cells were anchored onto the microbeads. This improved oxygen transfer rate was accompanied by higher production of penicillin at a lower aeration rate. Besides the improved oxygen transfer rate into the mycelial broth, a reduction of the energy input for the oxygen transfer was observed. The confinement of the cells to this microcarrier furthermore allowed the intermittent harvesting of fermentation broth without reducing the cell mass in the fermentor.