Manganese mine actinobacterial mediated gold nanoparticles synthesis and their antibacterial activity

Background and Objectives: Actinobacteria efficiently can produce different nanoparticles with different biological properties due to their ability to produce secondary metabolites. The aim of present study, isolation and screening of gold nanoparticles via producing actinobacteria from the soil were studied and their antibacterial activities was evaluate. Methods: In this study, after isolation of actinobacteria, the accumulation of gold nanoparticles was investigated by changing the color of the reaction medium and its adsorption by UV-visible spectrophotometry. Then, for confirmatory tests, ultraviolet and visible absorption spectroscopy, High-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering analysis were used. Phenotypic and molecular methods were used to study the nanoparticle producing actinobacterium isolate. The antibacterial activity of synthesized gold against pathogenic bacteria were investigated. Results: Among the 35 Actinobacteria strains tested, one strain was biosynthesized nanoparticles and showed the maximum absorption at 537 nm, which is the characteristic of gold nanoparticles. Dynamic light scattering analysis showed an average size of 44.4 nm. The minimum inhibitory concentration of gold nanoparticles against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus were 5.8, 11.7 and 11.7 μg/ml, respectively. Molecular analysis revealed that the Actinobacter isolate was Amycolatopsis sp. KMN. The isolate Amycolatopsis sp. strain KMN showed 99.82% homology to Amycolatopsis methanolica239. Conclusion: Overall, according to the results, nanoparticles biosynthesized using Actinobacter cell extract showed different properties, which make them a suitable candidate for further research in the field of nanomedicines. Keywords:   Actinobacteria; Gold; Nanoparticles; Green synthesizes; Antibacteria activity