Abstract: Recombinant B.subtilis MU108 was immobilized in PUF matrix for enhanced production of PGA. The results showed that PUF matrix was suitable for partial immobilization of recombinant cells in a three-phase bioreactor. With immobilized bacteria, the expression of PGA and the growth of cells were compared between batch cultivation in three-phase fluidized bed and continuous bioprocess in three-stage cultivation system. The productivity of PGA in batch cultivation was improved significantly with the increase of aeration. A new three-stage continuous cultivation system was designed and tested.It separated the whole process into three stages: cell growth, high temperature induction and PGA expression. After the beginning of nutrient continuous feed at mid or late log-phase,cell density, pH and residual glucose in the first- and third-stage bioreactor would be maintained steady up to 65 h. Compared with those in the batch fermentation, the average productivity of PGA was improved by 190% in the three-stage continuous fermentation, and the time for PGA expression was also extended from ca.10 h to ca. 60h. These results suggested that this new three-stage cultivation technique with immobilized cells might be very efficient for large-scale production of heterogeneous proteins.