## 2 Materials and Methods
### Maintenance of Unfavorable Growth Conditions for Rhizoctonia solani AG 2-2 IIIB via Biotic Factors  
To study the pathway to control _R. solani_ AG 2-2 IIIB via biotic factors, a microbial community from compost was used. Plant residues were used for composting. The compost sample was taken from the countryside in Opole region. Before the investigation, it was stored in the refrigerator at +5 \({}^{\circ}\)C. The species content of its microbiome was not identified, since there was no need to analyze it. The compost served as the source of microbial community. Though the composition of species in it can differ, their general function is the same: degradation of organic substrate reducing Eh and O\({}_{2}\) content in the medium [28; 29]. Creation of such conditions is necessary to suppress _R. solani_ AG 2-2 IIIB. To investigate the effect of microbial community on _R. solani_ AG 2-2 IIIB, the agar blocks with the fungus were inoculated in aerobic conditions into 150 mL flasks with 50 mL of peptone broth and 1 g of compost. The flasks were hermetically closed with silicon stoppers. The cultivation was carried out for 7 days at 25 \({}^{\circ}\)C. The fungus growth was observed via the measurement of the length of the mycelium. The cultivation of _R. solani_ AG 2-2 IIIB and microbial community was also conducted in separate flasks under the same conditions. The values of pH and Eh were measured potentiometrically via Elmerton pH/conductivity meter CPC-411, electrode pH EPS-1, and electrode redox ERS-2, respectively. To confirm the death of mycelium after cultivation, the agar blocks with Rhizoctonia were sequentially transferred from the flasks to peptone agar in Petri plates after each day of cultivation. For this purpose, the agar block was ground in the sterile mortar. The mixture was transferred onto peptone agar and spread over the surface with a Dryhalsky spatula. To confirm the effect of microbial community on _R. solani_ AG 2-2 IIIB, cultivation on a solid substrate imitating the structure of soil was conducted. To model it, glass balls with a diameter of 2 mm were used. Petri plates were used as cultivators. The Petri plates were filled with 3 layers of glass balls and nutrient broth. To create aerobic conditions, glass balls were placed into the bottom of Petri plates that were covered with a lid to provide oxygen access. To create anoxygenic and anaerobic conditions, balls were placed into the lid and covered with the bottom, used upside down. To create anaerobic conditions the solution of Fe(II) citrate (1 mL) was added to peptone broth. The limitation of oxygen access was achieved by filling the gap between the lid and the bottom with a mixture of petroleum jelly and paraffin in a ratio of 1:1 after the inoculation. The separate growth of _R. solani_ AG 2-2 IIIB and the microbial community as well as their joint cultivation were studied. The agar blocks (7 mm diameter) with the pre-cultivated Rhizotenia were placed in the center of the plates and used as the growth control. To study the effect of microbial community, a suspension of compost was prepared. For this, 1 g was diluted in 99 mL of peptone broth. This suspension (0.1 mL) was used to inoculate Petri plates. The cultivation took 7 days at 25 \({}^{\circ}\)C. The fungus growth was observed via the measurement of the length of the mycelium from the agar block to its distal part. To indicate the pH and redox potential of the medium in Petri plates, the indicator 0.01% bromothymol blue (BTB) was used. It changes color depending on the conditions: pH \(>\) 7--blue, pH = 7--green, 5 \(<\) pH \(<\) 6--yellow, and pH \(<\) 5--bright yellow. As the redox indicator, it turns colorless at Eh \(\leq\) \(-\)200 mV (pH = 7.0-7.8). Sodium resazurin solution (0.01%) was also used to control redox potential. At the potential above \(-\)50 mV, it is purple. At the potential range of \(-\)50 to \(-\)100 mV, it is pink, and at less than \(-\)100 mV, the colorless form is observed.