Fig. (1) Contour plots showing interactive effect of selected independent variables on ChOx activity (a) pH and inoculum size (b) pH and incubation temperature (c) pH and shaking speed (d) inoculum age and fermentation period (e) inoculum age and incubation temperature (f) inoculum size and fermentation period (g) inoculum size and incubation temperature (h) fermentation period and incubation temperature.