The Plackett-Burman design was used to screen and determine the key nutrients that can have a significant effect on MK-7 production.The levels of investigated variables are listed in Table2. While the Placket–Burman design does not evaluate the interaction
terms,it considerably reduces the number of experiments that are required to evaluate the main effects(Giordanoetal.,2011). The analysis of variance of the model parameters(ANOVA)on MK-7 production are presented in Table3. The regression coefficient was
0.957,which indicates that the model as fitted explains almost 96%
of the variability around the mean and confirms the good model fit.