## 3 Results
### Application of Biotic Factors for Control of Rhizoctonia solani AG 2-2 IIIB  
Alkaline pH, absence of O2, and low Eh created via abiotic factors are the key conditions shown to suppress _R. solani_ AG 2-2 IIIB. The application of microbial communities possessing a wide range of metabolic activity is also suitable as an effective tool to create such unfavorable conditions. Moreover, suppression can be enhanced due to the antagonistic properties of microbial exometabolites and even bacterial consumption of the dead mycelium as the nutrient source. In this regard, the application of microbial communities can provide effective control and irreversible suppression of _R. solani_ AG 2-2 IIIB. The co-cultivation of microbial communities from compost with _R. solani_ AG 2-2 IIIB revealed the following results (Figure 4). The control growth of _R. solani_ did not significantly change  
Figure 3: Effect of Eh and presence of O2 on _Rhizoctonia solani_ AG 2-2 IIIB growth: aerobic conditions (black line); anoxygenic conditions (red line); anaerobic conditions (blue line). pH (6.9-7.2) and Eh (+223... +257 mV). The length of mycelium reached 31 \(\pm\) 0.5 mm after 7 days. However, the growth of microbial community affected the medium pH and Eh. No significant difference was observed between the growth of microbial community and its cultivation together with _R. solani_ AG 2-2 IIIB. The pH decreased from 7.2 to 6.1, and Eh dropped from +251 to \(-\)125 mV during 7 days. Under these conditions, _R. solani_ AG 2-2 IIIB growth in the presence of microbial community was not observed. Since pH was favorable for _R. solani_ AG 2-2 IIIB, it was suggested that low redox potential and oxygen absence were the key conditions suppressing it. Moreover, the following transfer of the agar block, used as the inoculum of Rhiz to peptone agar, confirmed complete death of mycelium during the cultivation with microbial community. Even one day of co-cultivation was enough to completely suppress _R. solani_ AG 2-2 IIIB. Therefore, a microbial community can be effectively used to control _R. solani_ AG 2-2 IIIB. This happens due to the consumption of oxygen, the creation of low redox potential (\(-\)150 mV and lower), and possibly production of antagonistic exometabolites during the growth of microbial community. Similar patterns of _R. solani_ AG 2-2 IIIB growth interacting with the microbial community were confirmed during the cultivation on solid substrate (glass balls). Aerobic conditions allowed for the growth of mycelium, which reached 23 \(\pm\) 2.1 mm length after 7 days. Anoxygenic and anaerobic conditions inhibited _R. solani_ AG 2-2 IIIB. The microbial community actively grew in all variants (aerobic, anoxygenic, and anaerobic). Moreover, after 1 day of cultivation, even in aerobic conditions, it reduced redox potential to \(-\)200 mV and lower, which was indicated by the discoloration of sodium rezasurin and BTB. Under such conditions _R. solani_ AG 2-2 IIIB growth in the presence of the microbial community was absent. The following study of the opportunity to recover the growth of _R. solani_ AG 2-2 IIIB after 7 days of cultivation via its transfer to peptone agar was also confirmed. The mycelium started to grow on the second day after anoxygenic conditions. After anaerobic conditions, the growth recovery was absent. However, no growth of _R. solani_ AG 2-2 IIIB was observed after its joint cultivation with a microbial community under aerobic, anoxygenic, and anaerobic conditions. Therefore, microbial community plays a major role in not only inhibition, but also in the death of _R. solani_ AG 2-2 IIIB. The unconditional role of the microbial community in the death of _R. solani_ mycelium was also confirmed by the cultivation on its natural substrate (sugar beets) (Figure 5). Figure 4: Dynamics of pH (**a**) and Eh (**b**) during the growth of _R. solani_ AG 2-2 IIIB and microbial community: separate cultivation of _R. solani_ AG 2-2 IIIB (black line); separate cultivation of microbiome (red line); co-cultivation of _R.