## 3 Results and Discussion  
The highest scatter light (SL) values observed in the laboratory culture microbioreactor parallels for each strain are shown in Table 2, whereas the final optimized concentrations of culture media components based on Taguchi design are depicted in Table 3. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**\#Exp**} & \multicolumn{3}{c}{**Levels (Percent Concentration)**} \\ \cline{2-4}  & **Sucrose/Glucose (X1)** & **SPC (X2)** & **KH\({}_{2}\)PO\({}_{4}\) (X3)** \\ \hline (1) & 2\% & 2\% & 0.2\% \\ (2) & 2\% & 4\% & 0.4\% \\ (3) & 2\% & 6\% & 0.8\% \\ (4) & 5\% & 2\% & 0.4\% \\ (5) & 5\% & 4\% & 0.8\% \\ (6) & 5\% & 6\% & 0.2\% \\ (7) & 8\% & 2\% & 0.8\% \\ (8) & 8\% & 4\% & 0.2\% \\ (9) & 8\% & 6\% & 0.4\% \\ \hline \hline \end{tabular}  
* SPC—soy protein concentrate; #Exp—number of the experimental variant.  
\end{table} 
Table 1: L9 array for the design of media composition for all bacterial strains. Statistical analyses allowed us to conclude that in most variants the highest scatter light values (SL) were reported for variant Glucose or Sucrose no. (6), which was statistically significant from the others. In comparison to the reference media (TSB and 3 TSB) the values SL for media with SPC, glucose and sucrose were 3-10 times higher depending on the variant. The results obtained in the first stage of the experiment clearly indicate the media, which are interesting for further optimization work. The maximum SL values obtained in the optimization experiment based on three variables (X1, X2, X3) set the level of optimal component concentration of the medium for each strain (Table 3). Bacterial cultures were made with the optimized medium. The commercial medium TSB, at the concentration recommended by the manufacturer, was used for control samples, and was three times higher than recommended (Figure 1). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Run**} & \multicolumn{5}{c}{**Strains**} \\ \cline{2-6}  & _Bacillus megaterium_ & _Bacillus subtilis_ & _Pseudomonas_ & _Enterococcus_ & _Lectobacillus_ & _Leuncontococ_ \\  & & _fluorosens_ & _faceium_ & _plantarum_ & _mesenteroides_ \\ \hline
**TSB** & 147.4 \(\pm\) 10.0e & 134.7 \(\pm\) 12.2 cd & 220.1 \(\pm\)  
In the case of the glucose variant with _B. megaterium_ culture, the scatter light value was more than two times higher than that of the reference medium. For _B. subtilis_, the glucose optimization variant was more than three times higher than the reference TSB. For _L. plantarum_ and _L. mesenteroides_, the differences in scatter light values in glucose-optimized media were 12- and 15-times higher than for the reference medium, respectively. For the _E. facecium_ strain, the best results were obtained with the glucose variant, about 3.5 times higher than for the commercial medium. The commercial medium TSB was completely useless for _E. facecium_, _L. plantarum_, and _L. mesenteroides_. _P. fluorescens_ was the only strain which showed good growth with the commercial medium at a concentration three times higher than that recommended by the manufacturer. However, in this case, a very long adaptation phase which extended cultivation was observed. It can therefore be concluded that the medium based on glucose is the best solution for all tested strains. [PERSON] et al. [22] performed the optimization experiments using the Taguchi approach and achieved a 107% greater yield in _Lactobacillus_ bacteria density. Taguchi method was also used to optimize the cultures of _Bacillus_ and _Pseudomonas_, for biosynthesis of the enzymes proteinase and xylanase, and for the removal of mercury from the environment. This method was found to improve the required parameters by over 10%. By comparison, in our study, the microbial biomass yields were increased by up to 15-fold, depending on the strain. Regarding cost minimization, [PERSON] et al. [23] conducted research on the use of Taguchi approach for the optimization of medium with the lowest price.