Green synthesis of copper nanoparticles extracted from guar seedling under Cu heavy-metal stress by Trichoderma harzianum and their bio-efficacy evaluation against Staphylococcus aureus and Escherichia coli

Copper nanoparticles were successfully synthesized with the help of agriculturally beneficial fungus Trichoderma harzianum through a simple green and eco-friendly route. The objectives of this study were to: (1) evaluate the application of T. harzianum and assess the effect of guar plant cultivation on heavy metal contaminated lands of copper in municipal and industrial wastewaters, and (2) develop a method to increase the antibacterial effects on the risk of two bacteria (Staphylococcus aureus and Escherichia coli). Two factors were investigated: (1) two copper (Cu) levels, Natural Hoagland Arnold solution as a control, and application of 100 μL Cu in Hoagland Arnold solution, and (2) two bio-fertilizer levels, no application, and fungus application. TEM and SEM photographs showed that synthesized Cu-NPs had spherical shapes. The formations of Cu-NPs were corroborated by FTIR and XRD analysis. Furthermore, the MIC and MBC of Cu-NPs towards bacterial growth were evaluated. The Cu-NPs and T. harzianum fungi presented antibacterial activity against Gram positive and Gram negative bacteria. The results suggested that green synthesis of nanoparticles using guar extracts can increase their antibacterial effect. The effect of Cu and fungi on biochemical properties of guar was also investigated. The results showed that the highest antioxidant enzymatic activity and proline amino acid were obtained at 100 μL Cu and T. harzianum application. Moreover, the results suggested that the use of T. harzianum can be useful in increasing the resistance to heavy metal stress in plants by increasing the activity of some antioxidant enzymes and secondary metabolites.