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The biomass filtrate containing various metabolites of endophytic bacterial strain, Brevibacillus brevis PI-5 was used as a biocatalyst for reducing and stabilizing copper oxide nanoparticles (CuO-NPs). UV-Vis spectroscopy, Fourier transform infrared, transmission electron microscopy, scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), X-ray diffraction, and X-ray photoelectron spectroscopy were used for CuO-NPs characterization. A spherical, well-dispersed, and crystallographic structure with sizes of 2–28 nm was formed. The SEM-EDX confirmed the presence of Cu and O with weight percentages of 27.62% and 48.88%, respectively. The biological activities including antifungal, anticancer, and larvicidal of synthesized CuO-NPs were assessed using the fungal radial growth inhibition, MTT assay method, and mortality percentages, respectively. The obtained data showed that the CuO-NPs exhibit high activity in a dose-dependent manner. The growth of three phytopathogenic fungi, Fusarium oxysporum, Alternaria alternata, and Aspergillus niger was decreased by percentages of 64.5% ± 4.1%, 62.9% ± 0.3%, and 70.2% ± 2.3%, respectively at 300 µg·mL–1. Also, various clinical Candida spp. were successfully inhibited with varied zones of inhibition and minimum inhibitory concentration values in ranges of 6.25–50 µg·mL–1. The in vitro cytotoxicity exhibits target-orientation to breast cancer cells (T47D) at low concentration compared to normal cells (HFB4) with IC50 values of 122.3 ± 5.4 and 229.9 ± 5.7 μg·mL–1, respectively. The mortality percentages of I, II, III, and IV instar larvae of Culex antennatus were 60% ± 1.4%, 43.1% ± 1.1%, 36.2% ± 1%, and 32.1% ± 0.9%, at 10 mg·L–1 and increased to 86.9% ± 2.1%, 68.1% ± 1.7%, 64.4% ± 1.9%, and 53.1% ± 1.4% at 50 mg·L–1, respectively.

The biomass filtrate of the endophytic bacterial strain Bacillus amyloliquefaciens Fa.2 was utilized for the eco-friendly production of silver nanoparticles (Ag-NPs). The yellowish-brown color's optical properties showed a maximum surface plasmon resonance at 415 nm. The morphological and elemental composition analysis reveals the formation of spherical shapes with sizes of 5–40 nm, and the Ag ion comprises the major component of the produced Ag-NPs. X-ray diffraction confirmed the crystalline structure, whereas dynamic light scattering reveals the high stability of synthesized Ag-NPs with a polydispersity index of 0.413 and a negative zeta potential value. The photocatalytic experiment showed the efficacy of Ag-NPs to degrade methylene blue with maximum percentages of 73.9 ± 0.5 and 87.4 ± 0.9% under sunshine and UV irradiation, respectively, compared with 39.8% under dark conditions after 210 min. Additionally, the reusability of Ag-NPs was still more active for the fifth run, with a percentage decrease of 11.6% compared with the first run. Interestingly, the biogenic Ag-NPs showed superior antimicrobial activity against different pathogenic Gram-negative bacteria (MIC = 6.25 µg mL−1), Gram-positive bacteria (MIC = 12.5 µg mL−1), and uni- and multicellular fungi (MIC = 12.5 µg mL−1). Moreover, the biosynthesized Ag-NPs could target cancer cells (Pc3 and Mcf7) at low concentrations compared with normal cell (Vero) lines. The IC50 of normal cells is 383.7 ± 4.1 µg mL−1 compared with IC50 Pc3 (2.5 ± 3.5 µg mL−1) and McF7 (156.1 ± 6.8 µg mL−1). Overall, the bacterially synthesized Ag-NPs showed multifunctional features to be used in environmental catalysis and biomedical applications. [ABSTRACT FROM AUTHOR]

In the current investigation, the antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) formed by an aqueous extract of Psidium guajava leaves against foodborne pathogenic bacterial strains was investigated. To achieve this goal, 33 bacterial isolates were obtained from spoiled fruits. Among these isolates, 79% showed cellulase activity, 82% showed amylase activity, 81% exhibited xylanase potential, and 65% exhibited lipase activity. Moreover, 12 isolates showed complete hemolysis (β-hemolysis). The identification of these isolates was done using sequencing and amplification of 16s rRNA as Staphylococcus aureus (two strains), Pseudomonas syringae (one strain), E. coli (two strains), Salmonella typhimurium (two strains), Listeria monocytogenes (one isolate), Bacillus cereus (two isolates), and Bacillus subtilis (two isolates). The formed ZnO-NPs by aqueous Psidium guajava leaf extract were characterized using UV, FT-IR, TEM, EDX, XRD, DLS, and Zeta potential. The data revealed the successful formation of a spherical shape, crystallographic structure, and well-arranged ZnO-NPs. FT-IR showed the effect of different functional groups in the plant extract in the formation of ZnO-NPs through reducing, capping, and stabilizing of end products. Moreover, EDX analysis showed that the Zn ion occupied the main component of the produced NPs. Interestingly, the obtained bacterial strains showed varied sensitivity toward green-synthesized ZnO-NPs. The growth inhibition of foodborne pathogenic strains by ZnO-NPs was concentration dependent, forming a zone of inhibition in the range of 20–23 mm at a concentration of 200 µg mL−1, which decreased to 15–18 mm at 100 µg mL−1. Moreover, the values of MIC were 25 and 50 µg mL−1 based on the bacterial strain. Overall, the green-synthesized ZnO-NPs can be a useful approach for inhibiting the growth of spoilage bacterial strains that destroy fruits and hence reduce the harmful effects of traditional treatment methods on the environment and human health. [ABSTRACT FROM AUTHOR]

Herein, four endophytic fungal strains living in healthy roots of garlic were used to produce selenium nanoparticles (Se-NPs) via green synthesis. Penicillium verhagenii was found to be the most efficient Se-NPs producer with a ruby red color that showed maximum surface plasmon resonance at 270 nm. The as-formed Se-NPs were crystalline, spherical, and well-arranged without aggregation, and ranged from 25 to 75 nm in size with a zeta potential value of −32 mV, indicating high stability. Concentration-dependent biomedical activities of the P. verhagenii-based Se-NPs were observed, including promising antimicrobial activity against different pathogens (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Candida albicans, C. glabrata, C. tropicalis, and C. parapsilosis) with minimum inhibitory concentration (MIC) of 12.5–100 µg mL–1. The biosynthesized Se-NPs showed high antioxidant activity with DPPH-scavenging percentages of 86.8 ± 0.6% at a concentration of 1000 µg mL–1 and decreased to 19.3 ± 4.5% at 1.95 µg mL–1. Interestingly, the Se-NPs also showed anticancer activity against PC3 and MCF7 cell lines with IC50 of 225.7 ± 3.6 and 283.8 ± 7.5 µg mL–1, respectively while it is remaining biocompatible with normal WI38 and Vero cell lines. Additionally, the green synthesized Se-NPs were effective against instar larvae of a medical insect, Aedes albopictus with maximum mortality of 85.1 ± 3.1, 67.2 ± 1.2, 62.10 ± 1.4, and 51.0 ± 1.0% at a concentration of 50 µg mL–1 for I, II, III, and IV-instar larva, respectively. These data highlight the efficacy of endophytic fungal strains for cost-effective and eco-friendly Se-NPs synthesis with different applications. [ABSTRACT FROM AUTHOR]