No abstract

Rhizobia as useful soil bacteria can coexist with legume and fix nitrogen. Nanoparticles (NPs) are now widely used in various branches of science and silver (Ag) and zinc oxide (ZnO) NPs are the most widely used in this area. These particles finally enter in aquatic and terrestrial environments and probably have harmful effects on living organisms and environments. The aim of this study was to evaluate the effect of silver and ZnO NPs on Sinorhizobium meliloti and alfalfa symbiosis. S. meliloti bacteria were isolated from the alfalfa root nodules. Minimum inhibitory concentrations (MIC) of NPs were determined by agar dilution method. The effects of NPs on nodulation were studied by plant infection test in Jensen-nitrogen free agar medium. The gene expression of nitrogen fixation (nif gene) was evaluated in the presence of NPs by Real Time PCR. It was found that in the presence of NPs, the total length of treated plants and the number of nodules were decreased by increasing the concentration of NPs (1.25 to 10 μg/ml of AgNPs and 12.5 to 100 mg/ml of ZnO NPs) compared to the control plants (p ≤ 0.05). nif gene expression was decreased in the presence of sub MIC concentration of NPs.

Background: Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen causing a wide range of human infections. The organism is resistant to a wide range of antibiotics. The purpose of this study was to investigate the effect of AgNPs on pyocyanin pigment production of P. aeruginosa bacteria isolated from clinical specimens. Methods: In this study, 15 clinical isolates of P. aeruginosa were collected from different specimens of hospitalized patients. P. aeruginosa was detected by biochemical and molecular (detection of pbo1 gene by colony PCR method) methods and the MIC and MBC of AgNPs were determined by agar dilution method. Inhibition of P. aeruginosa pyocyanin production at AgNPs concentrations of 0, 0.3, 0.5, 1 and 1.5 mg/ml of was studied with OD of 520 nm. Results: The mean MIC and MBC of AgNPs were 1.229 and 1.687 mg/ml, respectively. Pyocyanin production was investigated for all isolates at different concentrations of nanoparticles, and their comparison showed that with increasing nanoparticle concentration, pyocyanin production significantly decreased (p<0.05). Conclusion: According to the results of this study, AgNPs had an inhibitory effect on P. aeruginosa and its pigment production and with increasing nanoparticles concentration, pigment production decreased; therefore, it seems that the nanoparticles can be used to treat and prevent diseases caused by P. aeruginosa.

The bio-green methods of synthesis nanoparticles (NPs) have advantages over chemo-physical procedures due to cost-effective and ecofriendly products. The goal of current investigation is biosynthesis of zinc oxide NPs (ZnO-NPs) and evaluation of their biological assessment. Water extract of Brassica napus pollen [rapeseed (RP)] prepared and used for the synthesis of ZnO-NPs and synthesised ZnO-NP characterised using ultraviolet-visible, X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscope and transmission electron microscope. Antioxidant properties of ZnO-NPs, cytotoxic and pro-apoptotic potentials of NPs were also evaluated. The results showed that ZnO-NPs have a hexagonal shape with 26 nm size. ZnO-NPs synthesised in RP (RP/ZnO-NPs) exhibited the good antioxidant potential compared with the butylated hydroxyanisole as a positive control. These NPs showed the cytotoxic effects against breast cancer cells (M.D. Anderson-Metastasis Breast cancer (MDA-MB)) with IC 50 about 1, 6 and 6 μg/ml after 24, 48 and 72 h of exposure, respectively. RP/ZnO-NPs were found effective in increasing the expression of catalase enzyme, the enzyme involved in antioxidants properties of the cells. Bio-green synthesised RP/ZnO-NPs showed antioxidant and cytotoxic properties. The results of the present study support the advantages of using the bio-green procedure for the synthesis of NPs as an antioxidant and as anti-cancer agents.

Background: E. coli is a common cause of urinary tract infection and bacteremia in humans. That is frequently resistant to β-lactam