Partial purification and characterization of keratinase produced by keratinolytic fungi, Earliella scabrosa A2 and Aspergillus flavus A11

Abstract

Chicken feather waste originating from the poultry industry and its processing is a potential source of protein and amino acids that can still be used as functional compounds. This study aimed to study the keratinolytic activity of local fungal isolates in vitro as a keratin-degrading agent. Keratinase secreted by keratinolytic fungal isolates were produced and characterized in 1% (w/v) Feather Meal Broth (FMB) composed of pure chicken feathers. Fungal isolates used in this study were A2 and A11 which were later identified based on ITS-rDNA genetic similarity to Earliella scabrosa and Aspergillus flavus, respectively. Crude enzymes were precipitated using an increasing ammonium sulphate salt gradient. The enzyme activity of Earliella scabrosa A2 and Aspergillus flavus A11 were 19 and 7.5 U/mL respectively. The crude enzymes showed an increase of activity during 80% of precipitation for isolate A2 with 10 U/mL and for isolate A11 with 18.6 U/mL. The specific activity after dialysis were 61.99 U/mg for isolate A2 and 75.11 U/mg for isolate A11. The optimum condition of keratinase activity for isolate A2 were at pH 7 and 30°C while isolate A11 showed its optimum activity at pH 8 and 45°C.