Central composite rotatable design
Central composite rotatable design (CCRD) was carried out to optimize the most significant variables by PBD for enhancing CMCase production. CCRD can provide mathematical models showing the interaction of independent variables for CMCase activity [17]. The three variables were designed with twenty trials at five different levels (-2, -1, 0, +1, +2) (Table 3). The results of the experiment were analyzed by analysis of variance (ANOVA). The role of each variable and, their interaction is explained by applying the following quadratic equation: