PARTITIONING OF EXTRACELLULAR PROTEASE FROM BACILLUS SUB TILlS IN PEGIPOTASSIUM PHOSPHATE AQUEOUS TWO-PHASE SYSTEMS

Abstract

The aqueous-two phase system (ATPS) has a great potential for use in the downstream processing of fermentation products. The partitioning of extracellular protease from Bacillus subtilis C 1 0 culture was carried out in ATPS formed by polyethylene glycol (PEG)/potassium phosphate. Factors that influenced the partition of the extracellular protease in this system, including the concentration and molecular weight of the PEG, and the potassium phosphate concentration were investigated. The optimal ATPS was 20% (w/w) PEG 6000 and 15% (w/w) potassium phosphate, pH 7.0. The partition coefficient for extracellular protease (Kptotease) was 4.99 with a top phase yield (Y) of 90.25% at room temperature. The extracellular protease specific activity of the top phase was 0.33 unit/mg in the same system. This process, therefore, is suggested to be a rapid and convenient method for protease purification