3.4 Important variables
To identify the important variables, MIE were applied to the DNN models
using multivalent output models (Figures 3J and 3L ).Figure 4 indicates the top 20 most important variables based on
the MIE calculations. Glycerol, phosphate, glutamic acid (Glu), and
trehalose or maltose indicated high average MSE in the case of both cell
growth and GFP production. Several of the amino acids observed were
representatives of important components. In order to examine the
numerical values of the important variables, we recalculated the
relationships between the number of input variables, ordered by
significance, and the MSEtest each learning were
indicated (Figure S3 ). The MSEtest decreased
along with an increase in the number of variables and converged minimal
values. The results meant that the thresholds of the importance values
for cell growth and GFP were 18 and 15, respectively. According to the
sensitivity analysis of the important variables, the M4 yeast extract
used for a basal medium containing Glu, trehalose or maltose, isoleucine
(Ile), lysine (Lys), phosphate, glycine (Gly), and aspartic acid (Asp)
were predicted to increase cell yields by less than 30% (Figure
S4 ). Simultaneously, Glu, glycerol, phosphate, and Lys were estimated
to increase the yield of GFP (Figure S5 ). Interestingly, almost
all of the important variables over the thresholds were estimated to
exert a slight effect on the cell growth and GFP yields.