Study of growth inhibition of Streptococcus salivarius andLactobacillus rhamnosus by Copper and Silver oxide Nanoparticles

Background and Aim : Human societies are still in difficulty encounter human pathogens, despiteadvances in personal health and control of various diseases. One of these problems is tooth decay,which causes annoyingly high mortality and financial losses in human societies. In recent years,nanotechnology has been able to make profound developments in the research and production ofvarious products. Therefore, in this study antibacterial effects of Silver oxide (AgO) nanoparticlesand Copper (Cu) are investigated through various microbial tests on two microorganisms ofStreptococcus salivarius and Lactobacillus rhamnosus, which act as primary colonizers in theformation of dental plaque.Methods : Streptococcus salivarius ATCC ۱۰۵۵۶, was purchased from the Biotechnology CellBank of Pasteur Institute of Iran and Actinomyces viscosus PTCC ۱۲۰۲ from the collection centerof Iranian industrial microorganisms. Copper NPs with ۴۰ nm and ۲۰ nm Silver oxide NPsprovided from US Research Nanomaterials. Following incubation of bacteria and differentconcentrations of nanoparticles including ۱۰, ۲۵, ۵۰, ۱۰۰ and ۲۰۰ ppm, optical density of cultureswere monitored for five hours every half hour. At ۳۰, ۶۰ and ۱۲۰ minutes after incubation, colonyforming unites of culture was determined.Results : Based on the results, it is observed that Cu NPs inhibit normal growth of the bacteria inliquid culture. Inhibition power of Cu NPs was more than AgO NPs. Also, studying on CFU inliquid test indicated that samples those treated by NPs, in comparison with control culture,displayed the significant reduction in the number of bacteria.Conclusion : Based on the data obtained in this test, Copper nanoparticles were detected morefatal and antibacterial than silver oxide nanoparticles and Lactobacillus rhamnosus was moresensitive than Streptococcus salivarius. It was also found that by increasing the concentration ofnanoparticles, their fatal rate increased significantly. According to other studies carried out in thisarea, which all prove antibacterial properties of these nanoparticles at low concentrations, thesenanoparticles can be used as antibacterial agents in combination with mouthwashes andtoothpastes in the market.

کلیدواژه ها:

Copper ، Silver oxide ، Streptococcus salivarius ، Lactobacillus rhamnosus ، Nanoparticle.