USE OF COLLOID CHITIN AND DIATOMACEOUS-EARTH IN CONTINUOUS CAKE-FILTRATION FERMENTATION TO PRODUCE CREATINASE

A recombinant Escherichia coli M15(pQE3208) producing creatinase was c ultured in a cake-filtration fermenter containing colloid chitin and d iatomaceous earth. The filter medium of this cake filtration was a hol low cylinder made of a 20 mu m stainless steel sieve located in the ce ntre of the fermenter. During filtration, colloid chitin, diatomaceous earth, and E. coli cells formed a film of filter cake on the 20 mu m sieve. The filter cake impeded the outward flow of cells from the ferm enter. By controlling the concentration of colloid chitin (3 g/litre), diatomaceous earth (6 g/litre), and the interval of air sparging (0.5 h), continuous cake-filtration fermentation achieved a cell density i n the reactor three times higher and specific creatinase activity 35% higher than in ordinary continuous fermentation. An operation mode has been proposed for continuous cake-filtration fermentation to implemen t the production of intracellular protein which is inversely related t o the growth rate of microorganisms. (C) 1998 Published by Elsevier Sc ience Ltd. All rights reserved.