Abstract
Nanosilver oxide exhibits strong antibacterial and photocatalytic properties and has shown great application potential in food packaging, biochemical fields, and other fields involving diseases and pest control. In this study, Ag(2)O nanoparticles were synthesized using Bacillus thuringiensis (Bt-Ag(2)O NPs). The physicochemical characteristics of the Bt-Ag(2)O NPs were analyzed by UV‒vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma emission spectrometry (ICP), high-resolution transmission electron microscopy (HR-TEM), and zeta potential. The phis-chemical characterization revealed that the Bt-Ag(2)O NPs are in spherical shape with the small particle size (18.24 nm), high crystallinity, well dispersity, and stability. The biopesticidal and antifungal effects of Bt-Ag(2)O NPs were tested against Tribolium castaneum, Aspergillus flavus, and Penicillium chrysogenum. The survival, growth, and reproduction of tested pests and molds were significantly inhibited by Bt-Ag(2)O NPs in a dose-dependent manner. Bt-Ag(2)O NPs showed higher pesticidal activities against T. castaneum than Bt and commercial Ag(2)O NPs. The LC(50) values of Bt, Ag(2)O NPs, and Bt-Ag(2)O NPs were 0.139%, 0.072%, and 0.06% on day 14, respectively. The Bt-Ag(2)O NPs also showed well antifungal activities against A. flavus and P. chrysogenum, while it resulted a small inhibition zone than commercial Ag(2)O NPs did. In addition, A. flavus showed much more sensitive to Bt-Ag(2)O NP treatments, compared to P. chrysogenum. Our results revealed that Bt-Ag(2)O NPs synthesized using B. thuringiensis could act as pesticides and antifungal agents in stored-product fields. KEY POINTS: • Bt-Ag(2)O NPs could be synthesized using Bacillus thuringiensis (Bt). • The NPs showed a high degree of crystallinity, spherical shape, and small particle size. • The NPs also showed excellent insecticidal and antifungal activity.