رسائل ماجيستير
English
2022
Microbial keratinase production using chicken feather waste
Afrah Hamed Abdullah Al-Subhiyah , Bahjah Al Riyami, Sivakumar Nallusamy
كلية العلوم-جامعة السلطان قابوس · عمان
Chicken feathers are one of the greatest sources of keratin. These wastes, on the otherhand, can be converted into valuable resources. This current study was conducted tovalorize these keratinized wastes to produce microbial keratinase, using the microbespresent on feathers. 15 keratinolytic bacterial strains and 15 keratinolytic fungal strainswere isolated. Among the isolates from the feathers, Aeromonas caviae was identified asan efficient keratinase producer. This bacterium showed high efficiency in featherdegradation (23 %) with a high enzyme activity of 42.59 U/mL at 72 h of cultivation. At168 h of cultivation, A. caviae produced 182.5 µg/mL of soluble protein. This solubleprotein contained 18 amino acids with their derivatives including; histidine, glycine,tryptophan, tyrosine, valine, and β-alanine, alanine, arginine, asparagine, creatine,glutamine, glutathione, isoleucine, leucine, lysine, methionine, cystine, taurine, ornithine,proline, and threonine. The keratinase production conditions were optimized using theResponse Surface Method. The obtained enzyme was partially purified using ammoniumsulfate precipitation and dialysis. Under optimum conditions of PH 9 and 80 °C akeratinase activity of 48.54 U/mL was obtained. The partially purified keratinase wascharacterized as a serine protease. It was activated by K+, Mg2+, Zn2+, and Na+, salts, andsolvents including, SDS, Triton X-100, DMSO, Isopropanol, and TWEEN 80 with anotable increase in activity of 6-10%. H2O2, 2-Mercaptoethanol, and acetonitrile slightlyinhibited the activity of keratinase. Moreover, the results revealed the ability of obtainablekeratinase to degrade other substrates including casein, gelatin and skim milk with higherrelative activity than the control. This study showed that keratinase produced by A. cavieaisolated from chicken feathers is a promising tool for different industrial applications.