highly significantP < 0.05
The linear term coefficient of X 2 , as well as the quadric term coefficients of X 1 2 , X 2 2 , X 3 2 , had highly significant (P < 0.05) effects on cell density (transformation at base 10 log) ( Table 4 ), so Eq.1 can be simplified as: After analysis of the lipopeptides yield data, the model linear term coefficients of X 1 , X 2 and X 3 , and the cross-product coefficients of X 1 X 2 , X 1 X 3 and X 2 X 3 were not signifi