Production, characterization and antioxidant potential of protease from Streptomyces sp. MAB18 using poultry wastes

Poultry waste is an abundant renewable source for the recovery of several value-added metabolites with potential industrial applications. This study describes the production of protease on poultry waste, with the subsequent use of the same poultry waste for the extraction of antioxidants. An extracellular protease-producing strain was isolated from Cuddalore coast, India, and identified as Streptomyces sp. MAB18. Its protease was purified 17.13-fold with 21.62% yield with a specific activity of 2398.36 U/mg and the molecular weight was estimated as 43 kDa. The enzyme was optimally active at pH 8-10 and temperature 50-60 ° C and it was most stable up to pH 12 and 6-12% of NaCl concentration. The enzyme activity was reduced when treated with Hg(2+), Pb(2+), and SDS and stimulated by Fe(2+), Mg(2+), Triton X-100, DMSO (dimethyl sulfoxide), sodium sulphite, and β-mercaptoethanol. Furthermore, the antioxidant activities of protease were evaluated using in vitro antioxidant assays, such as DPPH radical-scavenging activity, O2 scavenging activity, NO scavenging activity, Fe(2+) chelating activity, and reducing power. The enzyme showed important antioxidant potential with an IC50 value of 78 ± 0.28 mg/mL. Results of the present study indicate that the poultry waste-derived protease may be useful as supplementary protein and antioxidant in the animal feed formulations.