Biotechnological applications of enzymes
Although enzymes have been used in certain industrial processes for centuries, their precise role or even their identity was not known over most of this period. Often, they were utilized as components of intact cells, e.g. yeasts in the baking and brewing industries. The first enzyme to be made commercially available in a partially purified form was the acid protease, rennin (chymosin) as rennet, a crude preparation obtained from the fourth stomach of young calves, used to curdle milk in cheese production. In view of the varied problems faced, the trend has been towards increased utilization of microorganisms as sources of enzymes.