Azospirillum brasilense or/ and Azotobacter vinelandii are employed in agriculture as biofertilizers. The main target of the present study is to assess the effect of nitrogen fixing microorganisms to improve and boost medicinal plants therapeutic effectiveness and better growth using Datura stramonium as an indicator plant. The inoculation of Datura stramonium with Azospirillum or/and Azotobacter partially or completely counteracted the improvements on some minerals content and secondary metabolic mechanisms. Generally, the application of Azospirillum or/ and Azotobacter as biofertilizers enhance the metallic contents of Datura stramonium and improve therapeutic effectiveness.