Distribution of extracellular proteolytic activities among various yeast.

A general screening test for extracellular proteolytic activities was carried out on 24 cultures belonging to 14 genera of yeasts. The screening was performed using gelatine and casein as sole nitrogen sources under two sets of pH conditions. Potent proteolytic yeast cultures belonging to both Ascomycetes and Deuteromycetes were detected, particularly certain members of the genera Endomycopsis, Metschnikowia, Debaromyces, Rhodotorula, and Candida spec. Most detected proteolytic cultures were active on both casein and gelatine substrates, possibly suggesting one enzyme system in each case with wide substrate specificity. Physiological studies revealed that maximum proteolysis occurred after 3--4 days of aerobic incubation and that some strains were able to hydrolyze egg albumin.