Green synthesis of silver nanoparticles by endophytic Burkholderia plantarii and their protection efficacy against postharvest tomato soft rot

Tomatoes, a vital cash crop, are highly susceptible to postharvest soft rot caused by Pectobacterium carotovorum . Bio-synthesized silver nanoparticles (AgNPs), generated via a green synthesis approach, offer a promising strategy for managing postharvest diseases due to their potent antibacterial properties. In this study, the endophytic Burkholderia plantarii BpMS90 was shown to reduce silver ions to form AgNPs (Bp-AgNPs). These nanoparticles exhibited characteristic surface plasmon resonance peaks between 400–450 nm and had an average size of 78.04 ± 29.66 nm. In vitro assays revealed that Bp-AgNPs had a minimum inhibitory concentration of 0.625 ppm against P. carotovorum and demonstrated broad-spectrum antibacterial activity against six additional bacterial species. Microstructural analysis indicated that Bp-AgNPs inhibited P. carotovorum proliferation by compromising cellular integrity. Treatment with Bp-AgNPs significantly decreased the incidence of tomato soft rot and minimized postharvest weight loss. Additionally, 16S rRNA gene sequencing demonstrated that Bp-AgNPs preserved the relative diversity of endophytic bacterial communities in postharvest tomatoes, notably sustaining the relative abundance of Weissella species in comparison to diseased tomatoes. Metabolomic correlation analysis revealed that Weissella abundance was positively associated with L -phenylalanine, citric acid, and L -tryptophan levels, metabolites implicated in postharvest disease resistance. These findings highlight the potential of biosynthetic Bp-AgNPs as effective antimicrobial agents and support their application in sustainable postharvest disease management. • Silver nanoparticles synthesized using endophytic bacteria control tomato soft rot. • Nanoparticles disrupt bacterial cells and reduce post-harvest disease incidence. • Treatment preserves tomato quality by lowering rot and weight loss after harvest. • Beneficial bacterial population increased relatively after treatment, improving microbial community balance. • Disease resistance links to elevated L -phenylalanine, citric acid, and tryptophan.