Biodegradation of poultry feathers using a keratinolytic enzyme to produce feather meal

Abstract

The application of biotechnology through the utilisation of enzymes is considered an easy and inexpensive method of producing valuable products from poultry feather wastes. The present study describes production of a keratinolytic enzyme from Pseudomonas aeruginosa S-04, which showed efficiency for feather biodegradation. The production of extracellular keratinase was improved 1.3-fold through one factor at a time (OFAT) optimisation of various parameters. Ammonium sulphate precipitation and DEAE-cellulose anion exchange chromatography were used to purify the keratinase produced by P. aeruginosa S04 to homogeneity. Purified keratinase (35.5 kDa) showed optimal activity at 60°C and pH 9.5 and displayed stability over the pH range 7-9.5 and temperatures ranging from 4-40°C for 2 h. Catalytic activity of keratinase was enhanced in the presence of Fe3+ and Mn2+ ions, Triton X-100, Tween 20, DMSO, isopropyl alcohol and ethanol, but reduced activity was recorded in the presence of methanol and acetone. The enzyme activity was deactivated by EDTA, suggesting that this keratinase belongs to metallo-protease family. The Km and Vmax of the purified keratinase was found to be 7.62 mg/ml and 200 U/mg protein, respectively. The partially purified keratinase revealed great potential for feather degradation (93% in 24 h), and the nutritional content of the resulting feather hydrolysate makes it a promising candidate for application in the poultry industry.