Pleurotus albidus: A new source of milk-clotting proteases

Researches have been done to discover new sources of microbial proteases with milk-clotting activity to replace the traditional rennet from calves. The aim of this study was to select a species of edible mushroom as milk-clotting enzymes producer using the submerged fermentation technology. From the six species evaluated, Pleurotus albidus was the one that expressed the highest value of coagulant ratio (21.60). The milk-clotting enzymes showed maximum activity at 60°C and pH 6.0. Iodoacetic acid presented the highest inhibition in proteolytic activity suggesting the presence of cysteine proteases in the crude extract from P. albidus. The enzymes did not present toxic action against human fibroblasts (MRC5) in the analyzed conditions and, for that reason, can be suitable to applications in food industry. This is the first report of milk-clotting enzymes production by the edible mushroom P. albidus