Milk-clotting Enzymes from Microorganisms.

A total of 230 cultures of fungi and 43 cultures of bacteria, isolated from such sources as soil, butter, and milk, were screened for their milk-clotting activity. The fungi were cultivated on semisolid media, and the bacteria were grown in milk media in shake culture. Phytic acid, added as calcium phytate, was found to stimulate production of the enzyme in most of the bacterial isolates. Proteolytic activity was invariably found to be associated with the milk-clotting enzyme in bacterial isolates. There was considerable variation in the ratio of the two enzymes from strain to strain.