P. putida CH11 grown in 100 mL of plate count broth was harvested by centrifugation (7500g, 10 min) and then washed with sterile distilled water three times. The organisms (10
cells/mL) were immersed in a sterile 4% Na alginate solution, and then the Na alginate solution containing the cells was dropped into a 4% CaCl solution by syringe to immediately form 3 mm diameter immobilized beads. These gel beads were activated by flushing with sterile distilled water for 5 h. The activated beads exhibited excellent mechanical strength in the continuous experiments.