Protease enzymes are the enzymes that hydrolyse proteins. Each type of protease enzyme breaks specific kind of peptide bonds. These enzymes are of great commercial importance contributing to more than 40% of the world’s commercially produced enzymes. Approximately 50% of the enzymes used in industrial processes are proteolytic enzymes. Different substrates used for the protease enzyme production add to the cost and hence makes the process very costly. | Protease production from biodigested slurry of biogas plants: A review