Protease able to degrade keratin into peptides. Is responsible for keratinolysis by F.pennivorans, which allows this bacterium to grow on native feathers. Is inhibited by phenylmethylsulfonyl fluoride and 3,4-dichloroisocoumarin. EDTA and iodoacetate (1 to 5 mM) have only little effect on the enzyme activity. Optimum pH is 10. Is active in a broad pH range, namely, between pH 6.0 and 10.5. Optimum temperature is 80 degrees Celsius. Is active in a broad temperature range, namely, between 50 and 100 degrees Celsius. Thermostable. Is cell-bound, probably associated with the outer cell envelope. Is composed of four domains: a catalytic domain, two beta-sandwich domains that may mediate interactions with substrate, and the propeptide domain. Undergoes auto-proteolytic processing. Once cleaved, the propeptide can remain associated with the protease and blocks its activity. The physiological activation of fervidolysin is proposed to be achieved through the stepwise removal of the propeptide accomplished by several proteolytic cleavages that may not be autolytic. The thermostable keratinase of F.pennavorans is a promising enzyme for application in an industrial process. Native feathers produced as waste by poultry farming could be converted to peptides and rare amino acids like proline and serine. Belongs to the peptidase S8 family.