Fig. 5
![Fig. 5](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs43141-022-00315-6/MediaObjects/43141_2022_315_Fig5_HTML.png)
(a–c) Three-dimensional surface models of A. niger NRC114 α-galactosidase formation. For each figure, the absent two parameters were fixed at 0 levels (i.e. pH value, 5.5; mannose conc., 10 g/L; meat extract, 7.5 g/L; and incubation time, 5 days) while the effect of the other two variables was measured