Use of different adsorbents for sorption and Bacillus polymyxa protease immobilization

Proteases constitute one of the most important groups of industrial enzymes, accounting for at least 25% of the total enzyme sales, with two-thirds of the proteases produced commercially being of microbial origin. Immobilized enzymes are currently the subject of considerable interest because of their advantages over soluble enzymes or alternative technologies, and the steadily increasing number of applications for immobilized enzymes. The general application of immobilized proteins and enzymes has played a central role in the expansion of biotechnology and synthesis-related industries. Proteases have been immobilized on natural and synthetic supports. In the present work, a protease from Bacillus polymyxa was partially purified with 80% ammonium sulfate precipitation followed by dialysis and chromatography using a diethylaminoethyl (DEAE)-cellulose ion exchange column. Immobilizaiton was evaluated by using different adsorbents (chitin, chitosan, alginate, synthetic zeolite, and raw zeolite) and the storage stability and recycle of the immobilized protease determined. Immobilization yields were estimated to be 96% and 7.5%, by using alginate and chitosan, respectively, after 24 h. The yield of the immobilization was 17% for alginate at 16 h and the enzyme did not adsorb on the chitin, chitosan, synthetic zeolite, and raw zeolite.