Antibacterial activity of silver nanoparticles against Xanthomonas compestris var. compestris

Cabbage black rot, a disease caused by Xanthomonas compestris var.compestris (Xcc), has significantly impeded the growth and development of Chinese cabbage.In this research, silver nanoparticles (AgNPs) were synthesized using Solidago canadensis as the primary material, and their capacity to inhibit the growth of black rot pathogens was evaluated.The results indicated that the AgNPs exhibited a spherical morphology with an average particle size of 10.22 nm.The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against Xcc were determined to be 10 g/ml.In particular, the inhibition circle assay and growth curve evaluation showed a profound suppressive effect of AgNPs on bacterial proliferation.Furthermore, treatment with AgNPs resulted in structural damage to bacterial cells, a reduction in hydrogen peroxide tolerance, and significantly hindered biofilm development.Synergistic evaluations with Zhongshengmycin, an aminoglycoside antibiotic, highlighted a significant collaborative effect in enhancing resistance to black rot with a Fractional Inhibitory Concentration (FIC) index of 0.335.These in vitro results showed that the combined application of 1.25 g/ml AgNPs and 0.25 g/ml Zhongshengmycin could inhibit pathogen infestation on explants and thus significantly reduce the dose of antibiotics in production.This study can potentially provide novel insights into preventing and treating cabbage black rot.