a study on inhibitory effects of titanium dioxide nanoparticles and its photocatalytic type on staphylococcus aureus, escherichia coli and aspergillus flavus

backgrounds and objectives: photocatalyst titanium dioxide nanoparticles can oxidize organic and inorganic compounds of microorganisms in aqueous solutions after exposure to uv light. in the present study, the inhibitory effect of titanium dioxide and its photocatalyst type on aspergillus flavus , escherichia coli and staphylococcus aureus is investigated.   materials and methods: toxicogenic strains of staphylococcus aureus , escherichia coli and aspergillus flavus were cultured in their selective media and two groups of samples both included three different concentrations of nanoparticles (0.1, 0.5 and 1 g l -1 ) and two control samples without any nanoparticles were considered. the first category of samples was placed on the shaker for 20 min, and the second category was irradiated by a uv lamp while shaking for 20, 40 and 60 min on a rotary shaker. thereafter, they were cultured by using pour plate method in agar and after incubation the colonies were counted.   results and conclusion: based on obtained results the photocatalyst titanium dioxide had an inhibitory effect at concentration of 1 g l -1 at the highest timeframe (60 min). in addition, the test variables i.e. the type of bacteria, concentration of nanoparticles and time had a significant effect on the growth inhibition of microorganisms. regarding the economic aspects of contamination control and its importance in dairy products, application of photocatalystic nanoparticles of titanium dioxide is recommended.