Keratinase Activity of A Newly Keratinolytic Bacteria, Azotobacter chroococcum B4

Abstract

Keratinase is a proteolytic enzyme capable on degrading the hardy polymeric biomolecule or keratin. In recent days, the utilization of keratinolytic microorganisms is seen as a promising way in recycling the keratin wastes from the avian and mammalians into valuable derived products. Previous study has reported the presence of a keratinolytic bacterium, later identified as Azotobacter chroococcum B4 obtained from dump soils. The present study investigates the enzyme characteristics of keratinase produced by this strain based on the physical appearance of final degraded product using SEM, the molecular weight of keratinase using SDS-PAGE, the effects of nutrition (C/N-source) on strain production of keratinase and the enzyme stability in metal ions solution. The molecular weight of keratinase produced by A. chroococcum B4 was about 30 kDa. Both sucrose and tryptone supplementation increase the keratinase activity by 71.7 and 97.8 U/mL after 96 h of cultivation. Metal ions, Ca2+, Mg2+, Mn2+, Na+ , and K+ are regarded as activators by increasing the relative activity of keratinase by 117, 166, 111, 113, and 112% respectively, while phenylmethylsulfonyl flouride (PMSF) is regarded as inhibitor by decreasing the relative activity down to 31%. Based on the metal ion characteristics, this strain produced a serine-protease type of keratinase which may further studied for its application in the field.

Keywords

• azotobacter chrocoocum
• keratinase
• sucrose
• tryptone