Purification and characterization of a milk-clotting protease from Bacillus licheniformis strain USC13

Abstract

Aim: The study of a milk-clotting protease secreted by Bacillus licheniformis strain USC13. Methods and Results: Growth of B. licheniformis USC13 in LB medium resulted in the production of a serine protease with a molecular weight of 62 kDa processed to its mature form of 34 kDa, both forms were found in the extracellular medium. The enzyme exhibited typical milk-clotting kinetics. Conclusions: The capacity of this protease to produce milk curds could make it useful as a new source of milk coagulants. Significance and Impact of the Study: Cheese-making industry seeks for novel enzyme sources, and microbial coagulants have several advantages over animal and plant counterparts. The protease from B. licheniformis has the ability to produce milk curds although more studies about quality of both the enzyme and the milk curds formed should be carried out in the future to confirm its usefulness in the dairy industry. © 2007 The Authors.