Synthesis, characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from Streptomyces xinghaiensis OF1 strain

Abstract

We report synthesis of silver nanoparticles (AgNPs) from Streptomyces xinghaiensis OF1 strain, which were characterised by UV–Vis and Fourier transform infrared spectroscopy, Zeta sizer, Nano tracking analyser, and Transmission electron microscopy. The antimicrobial activity of AgNPs alone, and in combination with antibiotics was evaluated against bacteria, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, and yeasts viz., Candida albicans and Malassezia furfur by using micro-dilution method. The minimum inhibitory concentration (MIC) and minimum biocidal concentration of AgNPs against bacterial and yeast strains were determined. Synergistic effect of AgNPs in combination with antibacterial and antifungal antibiotics was determined by FIC index. In addition, MTT assay was performed to study cytotoxicity of AgNPs alone and in combination with antibiotics against mouse fibroblasts and HeLa cell line. Biogenic AgNPs were stable, spherical, small, polydispersed and capped with organic compounds. The variable antimicrobial activity of AgNPs was observed against tested bacteria and yeasts. The lowest MIC (16 µg ml−1) of AgNPs was found against P. aeruginosa, followed by C. albicans and M. furfur (both 32 µg ml−1), B. subtilis and E. coli (both 64 µg ml−1), and then S. aureus and Klebsiella pneumoniae (256 µg ml−1). The high synergistic effect of antibiotics in combination with AgNPs against tested strains was found. The in vitro cytotoxicity of AgNPs against mouse fibroblasts and cancer HeLa cell lines revealed a dose dependent potential. The IC50 value of AgNPs was found in concentrations of 4 and 3.8 µg ml−1, respectively. Combination of AgNPs and antibiotics significantly decreased concentrations of both antimicrobials used and retained their high antibacterial and antifungal activity. The synthesis of AgNPs using S. xinghaiensis OF1 strain is an eco-friendly, cheap and nontoxic method. The antimicrobial activity of AgNPs could result from their small size. Remarkable synergistic effect of antibiotics and AgNPs offer their valuable potential in nanomedicine for clinical application as a combined therapy in the future.

Visible Light Plasmon Excitation of Silver Nanoparticles Against Antibiotic-ResistantPseudomonas aeruginosa

“…Preliminary assays showed that the synthesized AgNPs displayed antimicrobial activity against P. aeruginosa. The minimal inhibitory concentration (MIC) of AgNPs was 10 µg/mL, which is comparable to values reported by similar studies for the same bacterium(42–44). However, when the AgNPs were exposed to light the MIC dropped to 5 µg/mL.…”

Biological Effect of Organically CoatedGrias neuberthiiandPersea americanaSilver Nanoparticles on HeLa and MCF-7 Cancer Cell Lines

“…Although AgNPs cytotoxicity has been found in several studies [14,[66][67][68][69], the molecular mechanisms involved are not completely understood [16]. AgNPs may trigger oxidative stress by reactive oxygen species (ROS) production [70,71] causing a variety of intracellular responses and alterations in antioxidant systems [72], which nally could lead to apoptosis or necrosis [73].…”

Synthesis and characterization of nontoxic silver nano-particles with preferential bactericidal activity

“…Moreover, silver ions, as a secondary oxidation process of AgNPs, contribute to the biocidal properties of AgNPs by affecting the transport and release of potassium (K + ) ions from the microbial cells [43]. The increase in membrane permeability may lead to more pronounced effects such as loss by leakage of cellular contents, including ions, proteins, reducing sugars and ometimes cellular energy reservoir (ATP) [49].…”