Activity of biogenic silver nanoparticles against isolates of Prototheca species from bovine mastitis

Prototheca spp. cause numerous infections in a wide variety of species, including treatment‐unresponsive mastitis. Thus, the search for an effective therapy is essential. Silver nanoparticles are compounds with high therapeutic potential. This study aimed to evaluate the susceptibility profile and morphological changes in Prototheca spp. treated with biogenic silver nanoparticles (Bio‐AgNP). The algaecide activity was evaluated in microplates by microdilution method, resulting in a MIC50 of 30 μg ml−1 and a MIC90 of 60 μg ml−1. Scanning electron microscopy demonstrated changes in the surface of Prototheca bovis cells following treatment. The algaecide activity of Bio‐AgNP suggests a therapeutic potential as a novel approach for the control of Prototheca spp. in bovine mastitis. Significance and Impact of the Study: Mastitis in cattle caused by Prototheca spp. is responsible for high economic damage to dairy farms, due to lack of effective treatment, resulting a need to dispose of the affected animals. In this study, biogenic silver nanoparticles were evaluated in vitro as a potential molecule for the treatment of proteothecosis, mainly mastitis, caused by Prototheca species. The obtained results are promising and further studies should be carried out to assess in vivo potential of the investigated silver nanoparticles.