RIFAMYCIN-B PRODUCTION BY NOCARDIA-MEDITERRANEI IMMOBILIZED IN A DUAL HOLLOW FIBER BIOREACTOR

Continuous production of rifamycin B was studied using Nocardia mediterranei (ATCC 21789) immobilized in a dual hollow fiber bioreactor designed for cultivating aerobic cells. In the reactor operation the volumetric productivity based on the volume occupied by the immobilized cells was 108 mg l** minus **1 h** minus **1 when air was used for aeration and was 143 mg l** minus **1 h** minus **1 with pure oxygen. These corresponded to 22 and 30-fold increases over the productivity of the comparable batch system. These high productivities were due to the high cell mass density of 550 g l** minus **1. However, the specific productivity of the cell was 30-40% of that in the shake flask culture. As the residence time of medium in the reactor increased, pH of effluent rose to an alkaline region that was outside its optimum condition (pH 6. 5-7. 0) and the yield and productivity decreased.