ABSTRACT
The extracellular alkaline protease activity of 8 bacterial isolates was investigated in shake and static cultures A 72 hold. Bacillus macerans showed the highest alkaline protease activity under shaking conditions [71.3 U/ml]. Entrapment of B. macerans cells in Ca-alginate, K-carrageenan or agar, increased the alkaline protease activity in the cultures by 1.60 and 1.37-fold, respectively. Cell leakage was relatively lower from alginate beads. Cell entrapment decreased the protein content in the culture supernatants by 20 to 30% that of the free cultures. Some properties of the crude enzyme were studied. Optimum enzyme and substrate concentrations were 1.22 mg protein/ml and 30 mg casein/ml, respectively. Optimum temperature for the enzyme activity was 45°C and optimum pH was 10. The enzyme showed its maximal stability at pH 10 retaining 66% of its activity after exposure to 55°C for 30 min, while it retained only 25% of activity at pH 11