Facile Biosynthesis of Tellurium Dioxide Nanoparticles by Streptomyces cyaneus Melanin Pigment and Gamma Radiation for Repressing Some Aspergillus Pathogens and Bacterial Wound Cultures.

Melanin pigment was attracted significant interest as a photo-protecting natural polymer which applied in different fields like nanotechnology, food processing and biomedicine. Streptomyces cyaneus is used for melanin biosynthesis after optimizing its medium requirements. Tellurium dioxide nanoparticles (TeO2 NPs) were biosynthesized by the optimized melanin and gamma rays at room temperature. TeO2 NPs were characterized by UV–Vis., XRD, FTIR, HRTEM, DLS, EDX, and SEM mapping analysis. Antimicrobial activity of TeO2 NPs was tested against some pathogenic fungi and bacteria. The non-controlled free radicals produced from gamma rays were stopped by the natural melanin (stabilizing and capping agent). A proposed reaction mechanism for TeO2 NPs production was investigated. Data received from HRTEM and DLS analysis were calculated the average particles size of the spherical TeO2NPs and were found to be 75.0 nm. TeO2 NPs possesses a promising antifungal potential towards Aspergillus flavus, Aspergillus niger, and Aspergillus fumigatus (30.0, 20.0, and 19.0 mm ZOI, respectively). As well, they have antibacterial potential against Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae (25.0, 18.0, and 15.0 mm ZOI, respectively). Based on TeO2 NPs characteristics as an encourage antimicrobial agent, it may be conducted as active ingredients in biomedicine, food processing and packaging and cosmetics. [ABSTRACT FROM AUTHOR]