Valorization of chicken feather waste into bioactive keratin hydrolysate by a newly purified keratinase from Bacillus sp. RCM-SSR-102

Abstract

The objective of this study is the characterization of a keratinase from Bacillus sp.RCM-SSR-102 and its application in the preparation of keratin hydrolysate from chicken feather waste. The purified KER102 keratinase was characterized as a serine-metallo protease having a molecular weight of 30 kDa with optimum pH and temperature of 10 and 50 °C respectively. The keratinase could retain 98% activity at pH 10 and above and 55% activity at 20% salt concentration. The KER102 keratinase was found to be stable in the presence of oxidizing agents, surfactants and organic solvents. The keratinase could also hydrolyze both soluble and insoluble complex protein substrates. The KER102 keratinase could hydrolyze up to 5% (w/v) feather releasing 1.7 ± 0.19 mg/mL soluble peptides. The feather keratin hydrolysate (FKH) had both antioxidant and antityrosinase activity. The IC₅₀ value of FKH in 2, 2-diphenyl 1-picrylhydrazyl (DPPH) radical scavenging activity (1.02 ± 0.01 mg/mL), 2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity (20 ± +00.04 μg/mL) and anti-tyrosinase activity (1.2 ± 0.22 mg/mL) was recorded. The FKH also had DNA protecting ability against oxidative damage. Antioxidant and anti-tyrosinase compounds have potential applications in the pharmaceutical and cosmeceutical industry. Hence, the purified keratinase can be a potential candidate for the production of antioxidant and antityrosinase compounds from chicken feather waste.

Keywords: Antioxidant activity; Antityrosinase activity; Bacillus sp. RCM-SSR-102; Feather keratin hydrolysate; Keratinase.