While growing a Bacillus cereus B5e/sz strain on a synthetic, feather-containing medium, keratins classified as fibrous proteins were biodegraded. Their hydrolysis occurred in the presence of keratinolytic proteases released into the environment. Those enzymes liquefied the insoluble native keratin, the chemically modified keratin, and, to a much higher extent, the soluble keratin. The bacterial keratinases constituted a mixture of relatively thermostable, neutral metalloproteases exhibiting a keratinolytic activity of 10.9 KU and a proteolytic activity of 90.5 PU. Using an in silico analysis, it was found that, within the amino acid sequence of chicken feather keratin, short bioactive peptides were present and an ACE inhibitor prevailed therein. The keratin hydrolysate could be a source of peptides for potential applications in food products.
keratin, keratinolysis, Bacillus cereus, proteases, bioactive peptides