## 4 Conclusions  
Compared to 16S amplicon-based metagenome analysis, the classical characterization of typical microorganisms associated with beet sugar plants are often based on cultural methods, as it only provides an incomplete picture of the real bacterial community. This observation is especially true for the samples from the high-temperature part of the extraction area, the juice of the central part of the tower, the tower juice and the cassette-juice mixture. The set of cultural-based methods has to be extended by specific media and culturing conditions for species such as _Geobacillus_ spp. and _Caenibacillus_ spp. Based on lab-scale experiments accompanied by industrial-scale administration of rosin acids, specific antimicrobial effects and their persistence could be clarified in this study. As a result of addition of the antimicrobial, the total number of bacteria and the production of metabolites such as L-lactic acid could be reduced. However, the rosin acids-based product was only effective for a certain time period. Then, microbial growth including the production of metabolites started again. Further studies will be necessary to investigate more in depth the effect of rosin acids on the cellular level of the bacteria, as well as its stability under processing conditions. Figure 3: Representative flow cytometer scatter plots of living, dying and dead bacterial cells stained with SYBR Green (FL1) and Propidium Iodide (FL3) (**a**) sampled from mini-fermenters treated with 3 mg/L rosin acid-based product (Defostab 220) compared to (**b**) mini-fermenters without treatment at different time points (Start: pH < 5.8, Start + 0.5 h and at the end of the trial period of 24 h). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Treatment** &
\begin{tabular}{c} **Analyzed** \\ **Parameter** \\ \end{tabular} & **Start** & **Start + 0.25 h** & **Start + 0.5 h** & **Start + 0.75 h** & **End** \\ \hline \multirow{2}{*}{Rosin acids} & L-Lactic acid (mg/L) & 586 \(\pm\) 83 & 655 \(\pm\) 73 & 676 \(\pm\) 50 & 676 \(\pm\) 47 & 956 \(\pm\) 265 \\ \cline{2-7}  & pH & 5.78 \(\pm\) 0.01 & 5.66 \(\pm\) 0.03 & 5.65 \(\pm\) 0.04 & 5.65 \(\pm\) 0.04 & 5.31 \(\pm\) 0.21 \\ \hline \multirow{2}{*}{No treatment} & L-Lactic acid (mg/L) & 681 \(\pm\) 41 & 838\(\pm\) 108 & 966 \(\pm\) 217 & 979 \(\pm\) 222 & 1410 \(\pm\) 219 \\ \cline{2-7}  & pH & 5.78 \(\pm\) 0.01 & 5.56 \(\pm\) 0.19 & 5.45 \(\pm\) 0.27 & 5.42 \(\pm\) 0.28 & 4.99 \(\pm\) 0.16 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: L-Lactic acid concentration and pH-value of samples treated with (3 mg/L) or without a rosin acid-based product and as monitored in mini-fermenter trials; values are expressed as mean and standard deviation of three independent trials. Start: pH < 5.8, start of treatment; End: End of trial, 24 h.  
**Supplementary Materials:** The following are available online at [[https://www.mdpi.com/2076-3](https://www.mdpi.com/2076-3)]([https://www.mdpi.com/2076-3](https://www.mdpi.com/2076-3)) 417/11/2/737/s1, Figure S1: Rarefaction curves of alpha diversity (Simpson and Shannon) of all samples of the industrial trail in 2017/2018 in an Austrian sugar beet factory using 3 mg/L rosin acid-based product (Defostab 220) compared with no treatment. Detailed sample description in Supplementary Table S1, Table S1: Data description of Supplementary Figure S1 including sampling code, sampling point, sampling date and treatment with 3 mg/L rosin acid-based product (Defostab 220) during the sugar beet process. 0: no treatment. **Author Contributions:** Conceptualization, C.K.M., F.E. and K.J.D. ; data curation, C.K.M. and C.U. ; funding acquisition, F.E. ; investigation, C.K.M. and C.U. ; methodology, C.K.M., C.U. and U.Z. ; project administration, C.K.M. and F.E. ; resources, F.E. and K.J.D. ; software, C.K.M. and U.Z. ; supervision, W.K. and K.J.D. ; validation, C.K.M. and U.Z. ; visualization, C.K.M. ; writing--original draft, C.K.M. ; writing--review & editing, C.U., U.Z., F.E., W.H., W.K. and K.J.D.