Background:Increasing antibiotic resistance in bacterial strains is a serious and growing threat to human health. Therefore, there have been significant efforts to develop new antimicrobials agents. More recently, nanoparticles (NPs) have emerged as promising antimicrobial agents. Therefore, development of new NPs possessing enhanced bactericidal effects is desirable. Previous studies showed that titanium dioxide (TiO2) nanoparticles due to its energy band gap (3.02 eV) had antibacterial activity under UV irradiation. In this work, we introduced biogenic TiO2 NPs with low energy band and having antibacterial activity without requirement of UV light. Methods: TiO2 NPs was synthesized using a green method mediated Vibrio VLC strain. Briefly, the cell free extract of bacterium was prepared and TiO(OH)2 solution as precursor was added. The white precipitate was collected and dried in an oven at 350 ℃ for 3 h and characterized by XRD, UV-visible, and TEM. The band gap was calculated using Tauc/David-Mott model. The antibacterial activities were identified by MIC value for both E. coli and S. aureus strains. Results: The XRD pattern showed diffraction peaks that were attributed to anatase phase. The band gap of the sample was calculated 2.24 eV. The TEM image displayed the spherical morphology and the NPs size between 6.77- 21.35 nm. The MIC value was calculated 125 μg/mL for both strains. Conclusions:Because the energy band gap of the sample lies in the range of visible light spectrum it could be activated without requirement of UV light. This is an advantage of our prepared NPs compared with the previous biogenic TiO2 NPs.

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