Sustainable exploitation of high-protein feather waste for green production of cold-adapted and detergent-stable keratinase by Penicillium oxalicum AUMC 15084.

Abstract

Limited research has investigated the ability of psychrophilic and psychro-tolerant microorganisms to produce cold-active keratinases, despite their potential as an efficient alternative for substrate conversion at reduced energy expenditure. A screening of 32 Penicillium and Talaromyces isolates for keratinolytic activity at temperatures of 5, 10, and 15ºC identified a promising P. oxalicum strain as the most potent at 10ºC, yielding 242.39 U/mL. Following six days of incubation at pH 8.0 and 15 °C with 0.2% yeast extract as the nitrogen source, the P. oxalicum strain exhibited keratinase activity of 359.42 U/mL. The keratinase underwent purification with a 4.13-fold increase, utilizing an MP 800 anion exchanger and Sephacryl S 200 , resulting in a specific activity of 684.46 U/mg and a yield of 5.34%. The SDS-PAGE analysis identified a keratinase with a molecular weight of 37.51 kD, exhibiting peak activity at pH 9.0 and 20ºC, with a specific activity of 721.8 U/mg. Mg²⁺, Zn²⁺, and Mn²⁺ enhanced keratinase activity by 156.0%, 140.60%, and 156.0%, respectively. The keratinase activity was significantly enhanced (p < 0.05) by the addition of 5 mM SDS (139.15%), 5 and 10% mercaptoethanol (1125.70 and 1327.0%, respectively), and 5 and 10% DMSO (128.30 and 227.40%, respectively). The dehairing potential of P. oxalicum AUMC 15084, utilizing crude keratinase on goat skin, demonstrated complete dehairing after 20 h at 20ºC with the crude preparation. This study provides a promising Penicillium oxalicum strain that could be used for production of cold-active keratinase. The effectiveness of the produced keratinase in the dehairing process was demonstrated as an environmentally friendly alternative to the traditional chemical procedure.