# Antimicrobial Effect of Submicron Complex Oxide Particles CsTeMoO\({}_{6}\) under Visible Light
## 2 Materials and Methods
### Testing the Antimicrobial Effect of Synthesized Materials on Reference Strains  
Test cultures of microorganisms were two species of fungi: active biodestructors of various industrial materials _Aspergillus niger_ van Tieghen VKMF-1119 and _Penicillium chrysogenum_ Thom VKM F-245 (All-Russian Collection of Microorganisms, IBPM RAS, Pushchino) and two species of bacteria: _E. coli_ ATCC 25922 (Gram-negative) and _S. aureus_ ATCC 6538 (Gram-positive) (American Type Culture Collection, Manassas, VA, USA). The experiments used fresh cultures of microorganisms prepared from lyophilized strains. Evaluation of the antibacterial activity of various chemical compounds is performed using these bacterial strains.  
A suspension of fungal spores (1 \(\times\) 10\({}^{4}\) spores/mL) and bacteria (1 \(\times\) 10\({}^{5}\) cells/mL for _E. coli_ and 1 \(\times\) 10\({}^{3}\) cells/mL for _S. aureus_) was prepared in sterile distilled water to assess the antimicrobial activity of the investigated metal oxide compound under visible light. The concentration of CsTeMoO\({}_{6}\) was 2 mg/mL.  
Experimental variants with test compounds were placed in glass bottles with 10 mL of suspension of microorganisms on orbital shakers at 150 rpm, and some of them were exposed to light, while others were kept in darkness. Both bacterial and fungal spore variants were exposed for 60 min, 120 min and 180 min. Controls were used for experiment variants that did not include the test compound.  
The antimicrobial activity of the CsTeMoO\({}_{6}\) on bacterial and fungal spores was assessed by the change in the titer of microorganisms after the exposure time, which was determined by the plate method (Koch method) by inoculating 0.1 mL of bacterial suspension on an nutrient agar for the cultivation of microorganisms (FBUN SRCAMB, Obolensk, Russia) and 0.1 mL of suspension of fungi on Czapek's agar (CZA) with the addition of bacteriological agar 20 g/L (Hispanagar s.a., Burgos, Spain) with subsequent accounting of the number of growing colonies of microorganisms. Chemically pure reagents were used to prepare CZA (g/l): NaNO\({}_{3}\)-2.0; KH\({}_{2}\)PO\({}_{4}\)-0.74; K\({}_{2}\)HPO\({}_{4}\)-0.3; KCl-0.5; MgSO\({}_{4}\cdot\)7H\({}_{2}\)O-0.5; FeSO\({}_{4}\cdot\)7H\({}_{2}\)O-0.01; sucrose-30.0. Petri dishes with cultures of bacteria were placed in a thermostat at 37 \(\pm\) 2 \({}^{\circ}\)C for 24 h, with cultures of fungi at 28 \(\pm\) 2 \({}^{\circ}\)C for 72 h.  
The fungal biomass were grown on a liquid (without agar) CZA medium on shakers (150 rpm) in 500 mL Erlenmeyer flask at 27 \(\pm\) 2 \({}^{\circ}\)C for 7 days to assess the antifungal activity against vegetative mycelium. The test compound at a concentration of 2 mg/mL was resuspended in 10 mL sterile CZA with in sterile bottles, and then weighed portions of fungal mycelium (50-100 mg) were added to them. All variants were placed on orbital shakers at 150 rpm for 120 and 240 min under dark and light conditions. Variants with fungal mycelium without the test compound served as controls.  
After each time of exposure, the mycelium (in all variants) from the bottles was transferred to Erlenmeyer flasks with 100 mL liquid CZA for growing for another 7 days under the same conditions. At the end of the cultivation period, the inhibitory effect of the studied substances was determined by the increase in mycelium biomass and expressed as a percentage of the control.