Anti- blight effect of green synthesized pure and Ag-doped tin oxide nanoparticles from Averrhoa bilimbi fruit extract towards Xanthomonas oryzae-the leaf blight pathogen of rice

Abstract

Green synthesis of nanoparticles using plant extract is a novel substitute for conventional chemical or physical methods. A simple green synthesis of pure and Ag-doped tin oxide nanoparticles from the fruit extract of Averrhoa bilimbi and their antibacterial activities have been demonstrated in this work. Silver has been doped into tin oxide for a perceived enhanced antibacterial activity. Techniques like UV-DRS, XRD, FTIR, and TEM were used to characterize the green synthesized nanoparticles. An average crystalline particle size of 2.6 nm was observed in XRD studies. Apart from the structural elucidation, the zeta potential values of the particles were also done. The antibacterial activity of pure and doped nanoparticles against the bacterial leaf blight pathogen, Xanthomonas oryzae was tested adopting standard assays employed in antimicrobial analysis. A significant advantage of using the biosynthesized SnO2 and its silver-doped variant was noticed in all the assays carried out. The impact of nanoparticle in the cellular protein leakage and the stress-induced enzyme release was carried out using Bradford’s method and DPPH assay respectively. Based on the biofilm inhibition studies, the inhibitory effect of the nanoparticles towards xanthomonadin and exopolysaccharide formation was reaffirmed. The DNA cleavage analysis carried out also was found to be a proof of the bactericidal effect of the nanoparticles. Overall results point to a promising use of Ag-doped SnO2 nanoparticles against the leaf blight disease caused by Xanthomonas oryzae in rice.