Biosynthesis and Characterization of Keratinolytic Protease from Actinobacterium Sp. in Solid State Culture

The aim of this study was to use agro-industrial residues for the production of a halotolerant keratinolyticprotease by Actinobacterium sp. in solid-state fermentation. Among various agro-industrial residues that were evaluated, apple pomace supported maximum protease production (8400 U/g material). The optimum conditions required for enzyme production were a fermentation period of 72 h, 10% (w/v) NaCl, pH 7.0, 120% (v/w) moisture and 10% (v/w) inoculum. The enzyme exhibited activity to a range of pH (7.0-9.0) and temperature (30-45°C), with optima at 8.0 and 40 °C, respectively. Most of the divalent ions tested stimulated the protease activity and Ca ion was required for its activity and stability. The enzyme was widely active at the range of NaCl concentration (5%-15%, w/v) and effectively degraded chicken feather. This protease could be useful in fish sauce fermentation and also in feed industry.