Dual Hollow Fiber Bioreactor for Aerobic whole Cell Immobilization

Abstract

Aerobically growing Escherichiacoli, Aspergillusniger and Norcardiamediterranei were immobilized in the interstitial space of a dual hollow-fiber bioreactor formed by a parallel arrangement of three microporous polypropylene hollow fibers contained within a silicone tubule. All three types of cells grew well and attained high densities to reach 550-600 g dry cell weight per liter of the cell containing volume. In the cultivation of E.coli, cell growth among the fibers was not uniform and leakage of cells through the fiber walls was observed. The unlimited growth of A.niger expanded the silicone fiber and compressed the inner fibers to reduce the substrate flow rates gradually to zero. Only Nocardiamediterranei was grown successfully to make possible long term operation of 50 days or more, producing antibiotics rifamycin B with a volumetric productivity of 125 μg/mL/h based on the volume occupied by the immobilized cells. This corresponds to a 30-fold increase over the productivity of a comparable batch system.