A genetic recombinant hEGF producer E.coli JM101 was immobilized in polyurethane foam matrix and a three-phase fluidized-bed bioreactor was used to produce human epidermal growth factor (hEGF).The results indicated that polyurethane foam is an adequate immobilization material. With the addition of polyurethane foam matrix

the free cell density

plasmid stability and hEGF productivity were higher than those without the foam matrix

respectively. The two-stage culture of the immobilized cells was further carried out

in which

the first stage was performed in a three-phase fluidized-bed bioreactor for cell growth and the second stage was performed in bubbling bed for product expression. At a dilution rate of 0.2h-1

after continuous cultivation for more than 60h

the free cell density and product expression were maintained relatively stable. The hEGF productivity was still higher than 140mg8226;L-1 and the fraction of plasmid-carrying was more than 27%. The hEGF productivity in two-stage process was higher than the batch process.