[1] They were initially classified as 'proteinases of unknown mechanism' by the Nomenculture Committee on the International Union of Biochemistry in 1978 with EC number 3.4.99 in 1983 (Owen et al., 1983).
Keratinase production has been reported in various microorganisms including fungi and bacteria, and occurs at near-alkaline pH and thermophilic temperatures.
The same year Noval et al. (1959) published another article on enzymatic decomposition of native keratin by Streptomyces fradiae.
He isolated an inducible extracellular homogeneous enzyme, which shows a 7.5-fold increases in its activity after DEAE cellulose column chromatography.
Williams et al. (1990) continued his work on enriched feather degrading culture and characterized the organism to its species level for the first time.
Dozie et al. (1994) reported a thermostable, alkaline-active, keratinolytic proteinasefrom Chrysosporium keratinophylum which was able to solubilize keratin in lactose-mineral salt medium with DMSO.