PRODUCTION OF ALKALINE PROTEASE BY BACILLUS-LICHENIFORMIS IN AN AQUEOUS 2-PHASE SYSTEM

Alkaline protease production by Bacillus licheniformis was studied in an aqueous two-phase system composed of 5% (w/w) polyethylene glycol 6000 (PEG 6000) and 5% (w/w) dextran T500. The top phase was continuous and rich in PEG while the bottom phase was dispersed and rich in dextran. The cells were retained in the bottom phase and at the interface. The two-phase system produced less enzyme in total amount than the control in the early phase, but after 50 h the enzyme produced in the control system decreased while the aqueous two-phase system continued its production and finally the total enzyme activity reached 1.3 times that of the control culture. In order to improve the productivity of protease, repeated batch cultivation were successfully carried out four times by optimizing the top phas composition of freshly added media, which resulted in 13.8, 35.9, 27.8 and 34.7 units ml-1 h-1 of protease based on the amounts of replaced top phases, respectively. © 1990.