Manganese Mine Actinobacterial Mediated Gold Nanoparticles Synthesis and Their Antibacterial Activities

Actinobacteria efficiently can produce different nanoparticles with various biological properties due to their ability to produce secondary metabolites. The present study aimed to examine the isolation and screening of gold nanoparticles via producing actinobacteria from the soil. We also studied their antibacterial activities.

In this study, after the isolation of actinobacteria, the accumulation of gold nanoparticles was investigated. This aim was achieved by changing the color of the reaction medium and its adsorption by UV-visible spectrophotometry. Then, for conducting confirmatory tests, ultraviolet and visible absorption spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and dynamic light scattering analysis was used. Phenotypic and molecular methods were applied to study the nanoparticle-producing actinobacterium isolate. The antibacterial activity of synthesized gold was explored on pathogenic bacteria.

Among the examined 35 Actinobacteria strains, one strain was biosynthesized nanoparticles; it indicated the maximum absorption at 537 nm, i.e., the characteristic of gold nanoparticles. Dynamic light scattering analysis revealed an average size of 44.4 nm. The minimum inhibitory concentration of gold nanoparticles against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus was 5.8μg/mL, 11.7μg/mL, and 11.7μg/mL, respectively. Molecular analysis data revealed that the Actinobacteria isolate was Amycolatopsis sp. KMN. The isolate Amycolatopsis sp. strain KMN presented 99.82% homology to Amycolatopsis methanolica239.

Overall, according to the obtained results, nanoparticles biosynthesized using Actinobacter cell extract suggested different properties, making them a suitable candidate for further research concerning nanomedicines.