Chymosin or
rennin is a
protease found in
rennet. It is produced by newborn
ruminant animals in the lining of the fourth stomach to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of
cheese. Bovine chymosin is now produced
recombinantly in ,
Aspergillus niger var awamori, and as alternative resource.