The aim of this study was to select keratin-degrading bacteria from JSC “Biocentras” collection and poultry processing plant wastewater, and to study their ability to degrade chicken feathers. Isolated from poultry processing plant wastewater bacteria was grown in basal media with feathers meal and showed high keratinolytic activity and protein content throughout the cultivation time. Bacterial strains B. licheniformis 511, B. subtilis I1, B. subtilis 717, and B. subtilis 103 suggested strongly of bacteria that produces keratinolytic activity in the cell free culture supernatants. The obtained results showed that maximum activity of keratinase is a function of cultivation time by the bacteria tested. B. subtilis 103 reached to its maximum level of keratinase production (152 U/mL) after 24 hrs, when over bacteria (148-242 U/mL) after 48 hrs. The good ability of selected bacteria to degrade feathers was detected. The best biodegradation of feathers was obtained using B. subtilis I-1. Over bacillus good degraded feathers as well.

The aim of this study was to identify and optimize significant technological parameters influencing keratinolytic enzyme production by A. fradiae 119 and to study its ability to degrade keratin. In the present work chicken feathers meal (CFM) was found to be an excellent substrate for keratinase induction by A. fradiae 119. The strain produced 164 KU/mL keratinolytic activity in basal medium containing 7.5 g/L CFM as the sole source of carbon and nitrogen. Increased keratinolytic activity was achieved in media with ammonium sulfate as nitrogen source, the application of additional nitrogen sources to media containing CFM slightly decreased keratinase synthesis. Optimal parameters of the cultivation process were determined: pH of cultivation medium – 7.2, temperature – 34 ºC and inoculum’s size – 8 %, using the response surface methodology. The yield of keratinase activity was increased by 46 % (267 KU/mL) after optimization of the cultivation process. The good ability of cultural liquid to degrade feathers and wool was detected.