Eco-friendly Suppression of Xanthomonas axonopodis pv. punicae: the Role of Lactobacillus helveticus PMP-6 in Pomegranate Disease Management

The present study evaluates the antibacterial efficacy of a bacteriocin synthesized by Lactobacillus helveticus PMP-6 (GenBank accession no. MT444488) against Xanthomonas axonopodis pv. punicae (Xpp-1), the etiological agent of bacterial blight in Punica granatum L. (Pomegranate). The bacteriocin underwent purification, leading to a substantial increase in its specific activity from 233.849 AUmg-1 to 3615.81 AUmg-1, confirming successful enrichment of the bioactive peptide. Antibacterial assays demonstrated inhibitory effects under optimal conditions of 40 °C and pH 7.0, with a Minimum Inhibitory Concentration of 300 µgmL-1 and a Minimum Bactericidal Concentration of 400 µgmL-1. The antibacterial effect diminished in the presence of proteolytic enzymes, suggesting its proteinaceous nature. SDS-PAGE profiling of purified bacteriocin revealed a molecular weight of approximately 17 kDa. Furthermore, a Detached Leaf Assay validated it’s in planta effectiveness, as no visible disease symptoms were observed in treated pomegranate leaves up to 96 h. of post-inoculation. Collectively, these results underscore the potential of L. helveticus PMP-6-derived bacteriocin as a environmentally sustainable biocontrol agent for managing bacterial blight disease of pomegranate, providing a viable alternative to conventional chemical pesticides.