CMCase, Avicelase, and FPU activities exhibited a pH optimum of approximately 4, while the pH optimum of P-glucosidase was between pH 5 and 6. pH adjustment was therefore investigated with the objective of uniformly inducing all three activities. Culturing at pH 4 for 2 days, followed by a shift to either pH 5 or 6 on the third day, resulted in a marked increase in the p-glucosidase activity of PC-3-7, but no beneficial effect was observed in the case of CDU-11 and of KDG-3, which was already of high [3-glucosidase activity (Table 3-4). On the basis of these findings, a scale-up experiment was conducted in a 1-kL tank using the semi-batch culturing method with 10% Avicel as a carbon source and soybean curd as a nitrogen source. The pH was controlled and shifted as described above. Results are shown in Fig. 3-6. With a shortened culture period of 12 days, elevated activities of 530 U/ml and 8 U/ml were obtained for CMCase and p-glucosidase respectively, with an elevated protein content of 40 mg/ml in the culture broth. The soluble protein content of the culture broth was 53 mg/ml, which was considered favorable.