Purification and characterization of keratinase from feather degrading bacterium useful for mosquito control--a new...

Every day, food processing industries release wastes, which are environmental menance. Chicken feathers have been discarded in bulk as waste from poultry industries, globally. Degrading these wastes, as unused disposals, without acquiring any additional benefits has led to an idea to develop a new technology. We have reported earlier that Bacillus thuringiensis serovar israelensis (Bti) can be used for biodegradation of feather waste for biopesticide production. In the present study, purification and characterization of keratinase from feather degrading bacterium (Bti) is reported. Protein precipitate obtained at Ammonium sulphate saturation at 60% level and Sephacryl S-200 column chromatography resulted in 2.3 and 11.68 fold purification of the enzyme respectively. The purity was revealed in SDS-PAGE by a single band of molecular weight of 40 kDa and it was characterized. The optimum pH of the enzyme shifted to a more neutral range (6.0-8.0) with the highest activity (7.0). The optimum temperature of the reaction was determined to be 30ºC. The keratinase enzyme retained 51% residual activity (303 U/mg protein) at 70ºC (60 min) and the half-lives of the enzyme were 130 minutes at 40ºC, 90 min at 50ºC and of 60 min at 70ºC, respectively. Keratinase activity was enhanced by calcium and magnesium ions while EDTA, PMSF, β- mercaptoethanol and manganese inhibited the activity. This is the first report investigating the keratinase from Bti degraded chicken feathers for the bio-synthesis of mosquitocidal toxins.