Nanobiological synthesis of silver oxide-doped titanium oxide bionanocomposite targeting foodborne and phytopathogenic bacteria

Fungi possess remarkable capabilities for metal speciation, dissolution, and mineral formation, which contribute to the production of mycogenic nanostructures. This study explores a green chemistry approach for synthesizing silver oxide-doped titanium oxide (Ag2O-doped 2 O-doped TiO2) 2 ) bionanocomposite utilizing Trichoderma virens. . The light yellowish fungal filtrate transformed into a dark brownish colloidal suspension after reacting with silver nitrate and rutile titanium (IV) oxide. X-ray diffractometry (XRD) unveiled the crystalline structure of the bionanocomposite (22.15 nm), showing the coexistence of cubic and rutile tetragonal phases of Ag2O 2 O and TiO2, 2 , respectively. Fourier-transform infrared spectroscopy (FTIR) showed the presence of functional groups of alcohols, phenols, nitro compounds, and aromatic amines derived from the cultural filtrate of T. virens. . Raman analysis revealed vibrational modes corresponding to Ag2O 2 O and TiO2 2 nanoparticles. Distinct sharp emission peaks characteristic to Ti, Ag, and O were depicted using energy dispersive X-ray (EDX) analysis. X-ray photoelectron spectroscopy (XPS) confirmed the presence of elemental valence states and binding energies of Ag, Ti, and O in the mycogenic nanocomposite. Field emission scanning electron microscopy (FESEM) revealed aggregation of polydispersed Ag2O-doped 2 O-doped TiO2 2 bionanocomposite, displaying spherical- and cuboctahedron-shaped nanostructures with rough surfaces. High-resolution transmission electron microscopy (HRTEM) showed the presence of circular-, semi-spherical-, hexagonal-, and polygonal-shaped monodispersed Ag2O 2 O NPs, with defined boundaries. The Ag2O 2 O NPs were obviously deposited on the sheet-like TiO2 2 NPs. Selected area electron diffraction pattern implied the polycrystallinity of the as-synthesized bionanocomposite. A broad antibacterial spectrum of the prepared bionanocomposite was attained against foodborne pathogenic bacteria; Escherichia coli (12.05 mm), Salmonella enterica (11.26 mm), and Staphylococcus aureus (11.44 mm) and phytopathogenic bacteria; Clavibacter michiganensis subsp. michiganensis (15.72 mm), C. . michiganensis subsp. capsici (10.80 mm), streptomycin-sensitive and-resistant Xanthomonas citri pv. citri (14.11 and 14.53 mm, respectively), and streptomycin-sensitive and-resistant Pectobacterium carotovorum subsp. . carotovorum (11.36 and 11.07 mm, respectively) using in vitro Kirby-Bauer method. Minimum inhibitory and minimum bactericidal concentrations were determined via a broth micro-dilution assay. FESEM revealed significant morphological alterations in bacterial cells upon treatment with the bionanocomposite, including deformed shape, rough surface, cell thinning, wrinkled cell wall, protrusions, cavitations, and cracks. These findings signify the successful mycosynthesis of Ag2O-doped 2 O-doped TiO2 2 bionanocomposite, which acted a potent antibacterial agent against a variety of foodborne and phytopathogenic bacteria, which could be employed in environmental, biomedical, agricultural, and food bio-processing applications.