RESUMO
Ten fungal strains were screened on different kinds of whey and permeate for their ability to produce proteinase enzymes. Rhizopus sp. NRC 5 was selected as a new isolate from acid whey characterized by its high proteolytic productivity when grown in submerged culture of acid whey for 5 days at 30C +/- 2. Addition of CaC12 to the fermentation medium [acid whey] stimulated the enzymes formation, while MgC12 inhibited the enzymes biosynthesis. The produced enzymes gave high proteolytic activity at acidic and alkaline pH [5.5 and 8]. Optimum reaction temperature and time for acidic and alkaline proteinase enzymes were 40C for 15 and 25 min, respectively. Maximum acidic and alkaline proteolytic enzymes activity was obtained at enzyme concentrations of 0.54 mg/ml besides substrate concentration of 2.0 g%