Study the influence of culture conditions on rennin production by Rhizomucor miehei using solid-state fermentations.

Investigations were conducted on the production of Rennin enzyme from the fungi Rhizomucor miehei 3420 NRRL using Solid-State fermentation. Wheat bran was used as a substrate. The influence of moisture content, incubation temperature, and the initial pH of fermentation medium were studied. The protein content, milk clotting activity (MCA), specific activity, proteolytic activity (PA), and (MCA/PA) ratio of the extracted enzyme were calculated after 4 days of incubation to evaluate the quality of the enzyme. The results showed that the optimal conditions for production were as follows: incubation temperature of 40 °C, moisture content of 60%, and pH of (3). Under these conditions, a production process of Rennin enzyme was established, and the values of protein content, milk clotting activity, specific activity, proteolytic activity, and (MCA/PA) ratio reached to 4 mg/mL, 600 SU/mL, 150 SU/mg, 45 PU/mL, 13.3 respectively.