Synthesis, Characterization, and Optimization of Green Silver Nanoparticles Using Neopestalotiopsis clavispora and Evaluation of Its Antibacterial, Antibiofilm, and Genotoxic Effects

Silver nanoparticles (AgNPs) have been used in a variety of biomedical applications in the last two decades, including antimicrobial, anti-inflammatory, and anticancer treatments. The present study highlights the extracellular synthesis of silver nanoparticles AgNPs using Neopestalotiopsis clavispora MH244410.1 and its antibacterial, antibiofilm, and genotoxic properties. Locally isolated N. clavispora MH244410.1 was identified by Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA. Optimization of synthesized AgNPs was performed by using various parameters (pH (2, 4, 7, 9 and 12), temperature (25, 35 and 45 °C), and substrate concentration (0.05, 0.1, 0.15, 0.2 and 0.25 mM)). After 72 hours of incubation in dark conditions, the best condition for the biosynthesis of AgNPs was determined as 0.25 mM metal concentration at pH 12 and 35 °C. Fungal synthesized AgNPs were characterized via spectroscopic and microscopic techniques such as Fouirer Transform Infrared Spectrophotometer (FTIR), UV-Visible Spectroscopy, and Transmission Electron Microscopy (TEM). The average size of the AgNPs was determined less than 60 nm using the TEM and Zetasizer measurement system (measured in purity water suspension). The characteristic peak of AgNPs was observed at ~414 nm from UV-Vis results. Antibacterial and genotoxic activity of synthesized AgNPs (0.1, 1, and 10 ppm) were also determined by using the agar well diffusion method and in vivo Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster. AgNPs exhibited potential antimicrobial activity against all the tested bacteria (Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) except Escherichia coli in a dose-dependent manner. AgNPs did not induce genotoxicity in the Drosophila SMART assay. 79.33, 65.47, and 41.95% inhibition of biofilms formed by P. aeruginosa were observed at 10, 1, and 0.1 ppm of AgNPs, respectively. The overall results indicate that N. clavispora MH244410.1 is a good candidate for novel applications in biomedical research.