Optimization of some parameters of solid state fermentation of wheat bran for protease production by a local strain of Rhizopus oryzae

Some parameters of the production of an alkaline protease by Rhizopus oryza e in the solid state fermentation of wheat bran were optimized. Using the o ptimum parameters of an inoculum age of 7 days, an incubation time of 9 day s, an amount of CZAPEK-DOX (liquid medium) of 6 ml/g bran and an incubation temperature of 33 degrees C, an activity of 50 U/g bran was achieved. The initial pH of the CZAFEK-DOX medium had little effect. Re-incubation of mou ldy bran with only fresh CZAPEK-DOX yielded 3 times total activity compared to single-cycle fermentation. As for the effect of the amount CZAFEK-DOX m edium, the water constituent contributed more to activity increase than did the salt component. The ARRHENIUS activation energies were 23 and 7.9 kcal /mole below and above the optimum of 33 degrees C, respectively. Tn all the studies, along with protease production, variation of protein content and specific activity were also observed. Attempts were made to explain the eff ects and also gauge their implications for large-scale production.