## 3 Results and Analysis
### Optimization of Enzyme Production Conditions for Strain Fermentation
#### 3.3.2 Response Surface Optimization Test Results  
Design Expert 8.0 was used to analyze the experimental data. Table 5 shows the results of optimization. We obtained the quadratic regression equation for independent variables and CMC enzyme activity: Y = \(-\)265.9339 + 2.0392 A + 2.8952 B + 0.5815 C + 0.00025 AB \(-\) 0.03235 AC + 0.007345 BC \(-\) 0.3357 A\({}^{2}\) \(-\) 0.008552 B\({}^{2}\) \(-\) 0.03586 C\({}^{2}\).  
Figure 5: Effect of rotation rate on the enzyme production conditions of JZ2. Different letters (a–d) on same curve in the figure indicate significant differences (\(p\) < 0.05) for enzyme activity.  
Figure 6: Effect of temperature on JZ2 enzyme production conditions. Different letters (a–e) on same curve in the figure indicate significant differences (\(p\) < 0.05) for enzyme activity.  
Table 6 shows the analysis of variance. The \(p\)-value of the regression model was 0.0013 < 0.01, indicating that the regression equation was statistically significant. The real relationship between the three factors and enzyme activity of the response value was indicated by the misfit term of the \(p\)-value, which was 0.1056 > 0.05. R\({}^{2}\) = 0.9447 indicated a high fit between the equation and the experimental results [34]. The regression model was proven to be effective. The coefficient of variation (CV = 7.66%) indicated good experimental repeatability and the equation's predictive ability for the experiment. Influencing factors on the enzyme activity of strain JZ2 were temperature (C) > fermentation time (A) > rotation rate (B). Temperature and rotation rate \(\times\) temperature (BC) significantly affected CMC enzyme activity at the selected factor levels. Temperature affected bacteria biosynthesis by altering the physical properties of the fermentation broth, such as the rate of dissolved oxygen and degradation and the uptake of certain substrates [35; 36]. The CMC cellulase activity results under the influence of temperature showed that the highest enzyme production occurred at 25.7 \({}^{\circ}\)C.  
Figure 7 shows the influence of various factors on the interaction of response values. A moderate temperature of 25 \({}^{\circ}\)C led to an increase in CMC enzyme activity before decreasing with increasing fermentation time (1-3 days) or rotation rate (170-190\(\times\)\(g\)). Compared with rotation rate, temperature significantly affected CMC enzyme activity. As shown in Figure 7 AC, a moderate fermentation time of 2 days led to an increase in CMC enzyme activity before decreasing with the increase in rotation rate (170-190\(\times\)\(g\)) or temperature (20-25 \({}^{\circ}\)C). The effect of temperature on CMC enzyme activity was more significant than fermentation time. As shown in Figure 7 BC, when the rotation rate was maintained at a moderate level (180\(\times\)\(g\)), the changes in CMC enzyme activity increased with increasing fermentation time (1-3 days) or temperature (20-25 \({}^{\circ}\)C). CMC enzyme activity was significantly affected by the interaction between rotation rate and temperature. The effect of temperature on CMC enzyme activity was more significant than that of the rotation rate.