Protease production by Rhizopus oligosporus in solid-state fermentation.

Rice bran was superior to other proteinaceous substrates for protease production by Rhizopus oligosporus ACM 145F in solid-state fermentation. Maximum protease yield was after 72 h. The optimal initial moisture content was 47% (a w=0.97). Dried, ground and resuspended fermented rice was the most pratical and effective inoculum preparation, although, in the laboratory, spore suspensions prepared directly from agar slants were more convenient. Inoculum density (from 10(2) to 10(7) spores/g substrate) and age (3, 5, 7 and 9 days) had little effect on protease yield.