Comparing the Effect of Various Cations on Bacteriophage Activity Against Xanthomonas euvesicatoria

Abstract

Bacterial Spot is a common plant disease that affects tomatoes and peppers. It is caused by four bacterial strains belonging to the Xanthomonas genus, which have developed increased resistance to current copper-based treatments. Due to copper’s phytotoxic properties, we proposed an environmentally safer bacteriophage-based biocontrol treatment. It was previously observed that Ca2+ supplementation of our phages at low concentrations resulted in prominent lytic plaque formation. Based on these findings, our goal was to test the effect of four other phytochemically significant cations (K+, Na+, Zn2+, and Mg2) in the phage-host infectivity system. We hypothesized that phage supplementation with these cations at concentrations ≤0.1mM will induce increased virulence activity against X.euvesicatoria. Plaque assay results showed that larger and clearer plaques were mostly observed in phages supplemented with divalent cations at concentrations ≤0.1mM. This study aims to address uncertainties regarding cation-phage interactions when tested against the growth of a phytopathogenic bacterium.