Synthesis of Gold Nanoparticles using Endophytic streptomyces and its Bactericidal Activities against Enteric Bacterial Pathogens

The present study aimed to report the rapid and one-step synthesis of gold nanoparticles (AuNPs) using the cell-free supernatant (CFS) of an endophytic Streptomyces sp. BDUSMP S05 isolated from Solanum trilobatum. The synthesized AuNPs were characterized by using UV-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDAX) spectroscopy and X-ray diffraction (XRD). The UV-visible spectroscopy (UV-vis) absorption of colloidal AuNPs displayed a surface plasma resonance (SPR) centred at 533 nm. FESEM micrograph analysis showed that synthesized particles were predominantly spherical with a 20-30 nm size range. Dynamic light scattering (DLS) analysis showed that the average particle size varied between 2-28 nm. Zeta potential analysis indicated the negative value of -35.2 mV characteristic for stable AuNPs. The synthesized AuNPs displayed significant antimicrobial activity against Gram-negative bacteria, including Eescherichia coli, Salmonella typhi and Vibrio cholerae compared to CFS alone. The results revealed that endophytic Streptomyces sp. potential to be used for the synthesis of antibacterial gold nanobased materials.