Biological synthesis of Fe 3 O 4 @Ag using Scenedesmus obliquus and evaluation of its effect on the expression of MexA‐B efflux pump genes in ciprofloxacin‐resistant Pseudomonas aeruginosa strains

Abstract

This study was conducted to biosynthesize [email protected] nanocomposite with Scenedesmus obliquus extract, and to evaluate its antibacterial potential against Pseudomonas aeruginosa. In addition, the effect of the synthesized nanocomposite on the expression of MexA-B efflux pump genes was investigated. The Fe3O4@Ag nanocomposite was characterized using X-ray diffraction spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Dynamic light scattering (DLS) as well as Zeta potential analyses. Minimum inhibitory concentration (MIC) of the nanocomposite alone and in combination with ciprofloxacin against P. aeruginosa strains was determined. Finally, the expression of MexA-B efflux pump genes among the bacteria treated with the nanocomposite was evaluated using quantitative real-time PCR. Based on the results, the proper synthesis of the nanocomposite with the diameter of 40 to 70 nm and acceptable stability was confirmed. The synthesized nanocomposite had lower MIC value (8–64 μg/mL) than ciprofloxacin (64–512 μg/mL) which shows stronger antibacterial potential of the nanocomposite. In addition, treating bacteria with the nanocomposite and ciprofloxacin caused a significant reduction of MexA-B genes compared to the cells treated with ciprofloxacin or nanocomposite alone. Thus, Fe3O4@Ag nanocomposite can improve the efficacy of ciprofloxacin against P. aeruginosa by reducing the expression of MexA-B efflux pump genes.