Mycofabrication of bimetal oxide nanoparticles (CuO/TiO2) using the endophytic fungus Trichoderma virens: Material properties and microbiocidal effects against bacterial pathogens.

Bimetallic oxide nanoparticles (NPs) have gained the interest of researchers owing to the synergistic mechanism of action by the elements present. Mycosynthesis of nanostructures is a promising, facile, and an environmentally friendly approach. In the present study, CuO/TiO 2 NPs were produced using the cell-free filtrate of the endophytic fungus Trichoderma virens. The reaction of the fungal filtrate with the two metal salts, CuSO 4.5H 2 O and TiO 2 , resulted in the mycosynthesis of the CuO/TiO 2 NPs. The prepared bimetal oxide NPs were characterized using XRD, FTIR spectroscopy, EDX, DLS, zeta potential analysis, XPS, Raman scattering, FESEM, and HRTEM. The mycosynthesized CuO/TiO 2 NPs exhibited diffraction peaks characteristic of the monoclinic CuO and tetragonal rutile TiO 2 crystal planes. Homogeneity and stability were observed as a result of the biological moieties present in the fungal filtrate, which capped the CuO/TiO 2 NPs. The prepared CuO/TiO 2 NPs were distributed as flake/plate-like and quasi-spherical/nanorod CuO and TiO 2 NPs, respectively. A broad-spectrum antibacterial effect was recorded, with zones of inhibition as follows: foodborne pathogens Escherichia coli (14.34 mm), Salmonella enterica serovar Typhimurium (11.32 mm), and Staphylococcus aureus (9.63 mm); and phytopathogenic bacteria involving Clavibacter michiganensis subsp. michiganensis (Cmm , 12.16 mm), C. michiganensis subsp. capsici (Cmc , 11.26 mm), wild type and streptomycin-resistant Pectobacterium carotovorum subsp. carotovorum (Pcc , 11.06 and 12.37 mm, respectively), and wild type and streptomycin-resistant Xanthomonas citri pv citri (Xcc , 12.48 and 12.69 mm, respectively). The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the CuO/TiO 2 NPs were determined using the broth microdilution assay. NP-treated bacterial cells at sub-MICs had rough surfaces with membrane defects and exhibited shrinkage, reduction of cell edges, cracks, and fractures on their surfaces. This study provides insights into the potential of the mycosynthesized CuO/TiO 2 NPs as alternative nano-antimicrobial agents, which could be employed for future biomedical, agricultural, and pharmaceutical applications. [Display omitted] [ABSTRACT FROM AUTHOR]