LAUSR

Abstract The demand for keratinolytic proteases has increased in recent years, in view of their applications in the feed, detergent, fertilizer, leather and textile industries. Recently, studies have focussed on exploration of new and inexpensive carbon sources for their production. Among keratin wastes, dog hair presents no utility and is an environmental concern. In this study, we evaluate the feasibility of using white and melanized dog hair (WDH and MDH, respectively) as alternative substrates for protease production by a Fusarium oxysporum strain. The effects of dog hair concentration, cultivation period, and medium pH on alkaline protease production were investigated using a central composite rotary design (CCRD) and response surface methodology (RSM). The optimization process increased protease activity 14.85- and 7.19-fold, using WDH and MDH, respectively. The alkaline proteases produced from WDH and MDH showed distinct biochemical characteristics. To our knowledge, this is the first report on biotechnological use of this problematic, waste residue. Our results open new avenues for conversion of dog hair into other valuable products, especially feed or fertilizer. Graphical Abstract