IMMOBILIZATION IN POLYELECTROLYTE COMPLEX CAPSULES - ENCAPSULATION OFA GLUCONATE-OXIDIZING SERRATIA-MARCESCENS STRAIN

In previous papers, it was shown that eukaryotic microbial systems can be encapsulated in polyelectrolyte complexes (PEG) prepared from sodi um cellulose sulfate and poly(dimethyldiallylammonium chloride) with m aintainance of vitality. In the present study, prokaryotic cells were successfully encapsulated in these PEG. Serratia marcescens B345 (IMET 11312) was chosen as a model organism. This strain converts gluconic acid to 2-ketogluconic acid. Since the 2-ketogluconic acid produced ha s very strong complexing properties, the number of applicable immobili zation methods is restricted Due to the high stability of PEC towards complexing agents these problems can be overcome by the described meth od. As already described in previous papers, a preimmobilization of ce lls in a PEC coprecipitate prior to capsule formation proved to be adv antageous also for encapsulation of bacilli. The mean productivity of the encapsulated S. marcescens cells was 1-4.4 g l(-1) h(-1) in compar ison to 5 g l(-1) h(-1) for free cells. The productivity Mns highly de pendent on the flow rare of the reactor. The encapsulated cells were u sed for 1,200 h in a continuous biotransformation process for the prod uction of 2-ketogluconic acid. (C) 1996 by Elsevier Science inc.