Microbial proteases, especially from Bacillus sp., have traditionally held the predominant share of industrial enzyme market (Gupta et al. 2002a, b) since they possess almost all characteristics desired for biotechnological applications.
Activity staining and protease inhibition assays showed that the introduction of cysteine mutations dramaticly reduced the activity of inhibitors against microbial proteases, such as subtilisin A from Bacillus licheniformis, protease K from Engyodontium album, protease from Aspergillus melleus.
Microbial proteases provide few advantages over proteases from other sources.
Different crude microbial proteases were applied for chitin extraction from shrimp shells.
The SC moiety of SIgA protects SIgA from degradation by host and microbial proteases and provides additional innate immune functions.
Food industries provide other important uses of residues, such as underutilized fish, and by-products from the fishing industries for the production of bioactive peptides using microbial proteases.
Though proteases are found in plants and animals, microbial proteases account for two-third of share in the commercially available proteases (Kumar and Takagi 1999).
Generally, microbial proteases have been produced by fermentation under controlled conditions.
The extensive diversity of microbial proteases in several physiological and industrial applications promoted search for newer protease inhibitors.
However, various animals, plants, and microbial proteases have been suggested as milk coagulants (Zhang et al. 2011), but still attention has been focused on production of milk-clotting enzymes from microbial sources (Silveira et al. 2005; Wu et al. 2013) due to their rapid growth, relative inexpensive growth substrate, and diverse properties.
