Novel Antibacterial, Cytotoxic and Catalytic Activities of Silver Nanoparticles Synthesized from Acidophilic Actinobacterial SL19 with Evidence for Protein as Coating Biomolecule

Abstract

Silver nanoparticles (AgNPs) have potential applications in medicine, photocatalysis, agriculture, and cosmetic fields due to their unique physicochemical properties and strong antimicrobial activity. Here, AgNPs were synthesized using actinobacterial SL19 strain, isolated from acidic forest soil in Poland, and confirmed by UV-vis and FTIR spectroscopy, TEM, and zeta potential analysis. The AgNPs were polydispersed, stable, spherical, and small, with an average size of 23 nm. The FTIR study revealed the presence of bonds characteristic of proteins that cover nanoparticles. These proteins were then studied by using liquid chromatography with tandem mass spectrometry (LC-MS/MS) and identified with the highest similarity to hypothetical protein and porin with molecular masses equal to 41 and 38 kDa, respectively. Our AgNPs exhibited remarkable antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. The combined, synergistic action of these synthesized AgNPs with commercial antibiotics (ampicillin, kanamycin, streptomycin, and tetracycline) enabled dose reductions in both components and increased their antimicrobial efficacy, especially in the case of streptomycin and tetracycline. Furthermore, the in vitro activity of the AgNPs on human cancer cell lines (MCF-7, A375, A549, and HepG2) showed cancer-specific sensitivity, while the genotoxic activity was evaluated by Ames assay, which revealed a lack of mutagenicity on the part of nanoparticles in Salmonella Typhimurium TA98 strain. We also studied the impact of the AgNPs on the catalytic and photocatalytic degradation of methyl orange (MO). The decomposition of MO was observed by a decrease in intensity of absorbance within time. The results of our study proved the easy, fast, and efficient synthesis of AgNPs using acidophilic actinomycete SL19 strain and demonstrated the remarkable potential of these AgNPs as anticancer and antibacterial agents. However, the properties and activity of such particles can vary by biosynthesized batch.

Biogenic nanosilver bearing antimicrobial and antibiofilm activities and its potential for application in agriculture and industry

“…Frontiers in Microbiology 10 frontiersin.org on the surface of the AgNPs (Elumalai et al, 2017;Wypij et al, 2022). The presence of biomolecules on the surface of synthesized AgNPs was confirmed by FT-IR measurements which revealed characteristic peaks.…”

“…However, several unassigned peaks were also recorded in the XRD analysis. It is suggested that these additional peaks arise due to the crystallization of the bioorganic phase on the surface of the AgNPs ( Elumalai et al, 2017 ; Wypij et al, 2022 ). The presence of biomolecules on the surface of synthesized AgNPs was confirmed by FT-IR measurements which revealed characteristic peaks.…”

“…The increased antimicrobial effect may be due to the binding of antibiotics to AgNPs. The molecules of antibiotics react easily with nanoparticles due to many active groups such as hydroxyl and amido groups ( Wypij et al, 2022 ). Hence, AgNPs may be covalently bound to streptomycin due to the presence of four-terminal –NH 2 groups in antibiotic structure.…”

“…A biosynthesis reaction was induced on sunlight for 1 h and then the reaction mixture was incubated at room temperature in the dark. AgNPs were collected by centrifugation at 13,000× g (Thermo Scientific, USA) for 1 h and dried at 37°C (Thermo Scientific, USA; Wypij et al, 2022 ).…”

“…The physico-chemical analyses were performed as previously described by Wypij et al (2018Wypij et al ( , 2022.…”