Production of rennin-like enzyme by Absidia cylindrospora

Abstract

The composition of the culture medium influenced the production of extracellular and intracellular milk-clotting and proteolytic enzymes by Absidia cylindrospora. An appreciable increase of both enzyme activities, particularly proteolytic, was found when using molasses instead of sucrose. The use of milk whey as nitrogen source favoured production of the extracellular caseinase and intracellular milk-clotting enzymes. Corn-steep favoured production of extracellular milk-clotting more than proteolytic enzymes. A maximum milk-clotting/proteolytic activity ratio was reached at a corn-steep N concentration of 1·0 g/litre and C/N ratio of 21:1. Potassium dihydrogen phosphate concentrations below or above 1·0 g/litre had an adverse effect on the milk-clotting/proteolytic activity ratio, while addition of magnesium sulphate to the culture medium did not significantly affect production of the milk-clotting enzyme. An initial pH value of the culture medium of 5·0 gave the highest milk-clotting/proteolytic activity ratio and hence good rennin properties of the enzyme.