Green Biosynthesis of Silver Nanoparticles from Olive and Walnut-Related Bacteria, Synthesis, Characterization, and Antimicrobial Activity.

Many studies have demonstrated the effectiveness of various plant extracts in the synthesis of silver nanoparticles. The phytochemical components of plant extracts contain biodegradable agents necessary for the stabilization and synthesis of nanoparticles. However, extracellular components of microorganisms have been shown to have similar activity in recent years. This study expects nanoparticle synthesis using silver nitrate using bacteria from different plant and soil parts in the Proteobacteria and Actinomycetes families in the endophytic and free form obtained from various sources, determining their antimicrobial properties on other pathogenic microorganisms. Nanoparticules showed a positive effect on antibiotic-resistant human pathogenic bacteria (Staphylococcus, Escherichia, and Acinetobacter), two strains of the human pathogenic Candida, and six different plant pathogenic fungi (Aspergillus, Fusarium, Gaeumannomyces, and Penicillium) compared to the reference antibiotics and antifungals. The physical forms and dimensions of the nanoparticles were determined by XRD, FTIR, UV-vis, and scanning electron microscopy. We believe that our findings will be the basis for the bacterial nanoparticle production procedures. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01127-z.

Isolation, plant growth-promoting traits, antagonistic effects on clinical and plant pathogenic organisms and identification of actinomycetes from olive rhizosphere.

Soil actinomycetes are a highly common group of bacteria and frequently studied as having secondary metabolites in the potential of producing the most preferred antagonistic content. Considering the continuous variation in soil structure, there is a potential for encountering different organisms. Almost all of antibiotic contents are produced by these bacteria and their importance increase. In this study, eleven different actinomycetes strain were isolated from the rhizosphere of olive trees investigated for their plant growth-promoting (PGP) traits including ammonia production, indole-3-acetic acid production, phosphate solubilization, and siderophore production with antagonistic activities against a set of pathogenic bacteria, fungi, and yeasts. All actinomycetes were identified according to 16S rRNA regions were recognized in four different Streptomyces species but according to fatty acid analysis, there would be at least six different organisms. The potential for antagonistic and plant growth-promoting traits of olive tree rhizosphere actinomycetes were a promising tool for agricultural applications and clinical antibiotic resistance. Differentiation of organisms with the antagonism of pathogenic activities and PGP features could be a definitive method for future studies.

Synthesis, characterization and antibacterial activity of silver-doped TiO2 nanotubes.

One-dimensional titanium dioxide (TiO2) nanotubes (TNTs) doped with silver (Ag) (% 5) were synthesized via two-step hydrothermal method. These nanotubes were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The impact of Ag-doped TiO2 nanotubes as antibacterial agents against three strains of Gram positive Staphylococcus aureus and a strain of Gram negative Escherichia coli was also investigated. XRD, FT-IR and Raman spectroscopy results showed that nanotubes were complete anatase phase. The potential biocidal effect of nanotubes to different S. aureus strains and E. coli was obtained.