Exploration of chrome shaving hydrolysate as substrate for production of dehairing protease by Bacillus cereus VITSN04 for use in cleaner leather production

Abstract

Chrome shavings (chromium complexed collagenous waste scrapings), one of the major proteinous solid wastes of leather industry are posing a pollution threat. Recovery and reuse of protein component of the waste can prevent their disposal as landfills. In the present work, the collagen hydrolysate derived from chrome shavings was screened as an inexpensive protein source in comparison with agro based protein wastes for the cost-effective production of dehairing protease. The chrome shavings used in the study were obtained during processing of goat skins. Maximum enzyme production of 203 ± 0.07 U/mL by Bacillus cereus VITSN04 was observed with the formulated medium (pH 8.0) containing, 12 g/L of collagen hydrolysate from chrome shavings, 15 g/L of molasses, 3 g/L of K2HPO4, 2 g/L of NaCl and 0.04 g/L of CaCl2. Fluorescence spectral analysis confirmed that collagen hydrolysate stabilized the protease and prolonged its activity. The protease was purified with a yield of 88.1% using 22% (w/v) of 2-propanol and 14% (w/v) of K2HPO4 aqueous two phase system. The purification and activity of the enzyme was confirmed by native-polyacrylamide gel electrophoresis. The purification yield of protease with aqueous two phase system was much higher than that with ultrafiltration system. Thus, approach made in the present study provides an attractive option for recycling chrome shavings waste as a cheaper protein source in the production of dehairing enzyme for use in cleaner leather processing.