Characterization, Antimicrobial and Antioxidant Evaluation of Biofabricated Silver Nanoparticles from Endophytic Pantoea anthophila

Abstract

Endophyte mediated nanoparticles fabrication were emerging as a new frontier in nanomedicines that produce high biocompatible and functionalized silver nanoparticles. In this study, silver nanoparticles were successfully biosynthesized from the extracellular extract of endophytic bacterium Pantoea anthophila isolated from the stem of Waltheria indica for the first time. The synthesized nanoparticles showed a strong absorption band at 410 nm in the UV–Visible range. The dynamic light scattering and zeta potential analysis indicated that the average particle size was 16 nm at 5.30 mV. FTIR spectrum displayed the presence of various functional groups at 3423.65, 1633.71, 1022.27, 607.58 cm −1 that stabilised the nanoparticle. X-ray diffraction peaks were conferred to 100, 200, 220 and 311 planes of a face centred cubic structure. TEM and SEM micrograph revealed the spherical-shaped, polycrystalline nature with the presence of elemental silver analysed by EDAX. Selected area electron diffraction also confirms the orientation of silver nanoparticles with X-ray diffraction analysis. Antimicrobial activity against 10 different human pathogenic bacteria and fungi showed a broad spectrum inhibition against both Gram-positive and Gram-negative bacteria. Among the bacterial pathogens, B. Subtilis exhibited low activity compared to other pathogens. C. albicans was greatly controlled than other fungal species. A strong free radical scavenging activity of silver nanoparticles with IC 50 values 31.29 ± 0.73, 19.83 ± 1.57, 35.64 ± 0.94, 42.07 ± 1.30, 29.70 ± 2.26, 29.10 ± 0.82, 36.80 ± 0.63 μg/ml was obtained in different antioxidant assays that were comparable to the reference. The study suggests that the silver nanoparticles can be biosynthesized from endophytic P. anthophila metabolites with significant therapeutic potential. With proper validation, the biosynthesized silver nanoparticles can be developed as a promising antiviral and anticancer drug candidate.

Green Nanoarchitectonics of Silver Nanoparticles for Antimicrobial Activity Against Resistant Pathogens

“…Noteworthy that the AgNPs synthesized from bacterial strains showed greater antibacterial activity in comparison with metallic nanoparticles synthesized by physicochemical methods, due to the presence of proteins that can interact with biomolecules, resulting in greater biocompatibility, which can act mainly in cell lysis, through a change in membrane potential, loss of cytoplasmic material and inhibition of the respiratory chain [14][15][16][17].…”

Synthesis of Sodium Alginate–Silver Nanocomposites Using Plasma Activated Water and Cold Atmospheric Plasma Treatment

“…As seen from the figure, the transparent colorless pure alginate solution changed its color to the characteristic pale orange and dark brown colors of silver nanoparticles. The reduction of Ag+ to Ago is responsible for the color change of the solution due to the excitation of surface plasmon resonance in AgNPs [ 26 ]. The intensity of the color depended on the concentration of AgNP produced.…”

Endophytic Microorganisms From the Tropics as Biofactories for the Synthesis of Metal-Based Nanoparticles: Healthcare Applications

“…isolated from Rauvolfia tetraphylla (Hemashekhar et al, 2019); and CuO, Fe 3 O 4 , NiO and ZnO NPs obtained from different endophytes from tropical environments (Ganesan et al, 2020;Mani et al, 2021;Mousa et al, 2021). Nirmala and Sridevi (Nirmala and Sridevi, 2021) isolated the endophytic bacterium Pantoea anthophila from Waltheria indica in order to synthesize Ag NPs and evaluate its antioxidant and antimicrobial ability. To determine the antioxidant potential, the authors used the DPPH, ABTS, H 2 O 2 and superoxide (O 2 − ) radical scavenging assay and FRAP assay.…”

“…To determine the antioxidant potential, the authors used the DPPH, ABTS, H 2 O 2 and superoxide (O 2 − ) radical scavenging assay and FRAP assay. The NPs showed an excellent antioxidant activity that can be applied in various oxidative stress-related degenerative diseases (Nirmala and Sridevi, 2021).…”