# Antimicrobial Activity of LysX and LysP Endolysins Against Pseudomonas syringae pv. syringae and Xanthomonas arboricola pv. juglandis

## TL;DR

This study explores the use of endolysin enzymes as a new, eco-friendly way to control bacterial plant diseases caused by Pseudomonas syringae and Xanthomonas arboricola.

## Contribution

The study identifies and evaluates two recombinant endolysins with strong antimicrobial activity against two plant pathogens.

## Key findings

- LysP and LysX reduced the viability of Pseudomonas syringae by 62–78.3%.
- LysP and LysX reduced the viability of Xanthomonas arboricola by 51.5–53.1%.
- Endolysins show promise as biocontrol agents for plant bacterial diseases.

## Abstract

Pseudomonas syringae pv. syringae and Xanthomonas arboricola pv. juglandis are the causal agents of bacterial canker in cherry and walnut blight, respectively, which cause significant production losses worldwide. These diseases have traditionally been controlled by copper-based agrochemicals and, more recently, antibiotics. However, the prolonged use of these compounds has led to the emergence of resistant bacterial strains. The search for new, efficient, and environmentally friendly biocontrol alternatives has intensified. Phages are promising candidates due to their ability to specifically infect and lyse bacterial pathogens. Endolysin enzymes are responsible for bacterial cell wall degradation, and although they have been extensively studied in medical and veterinary contexts, their application in agriculture remains limited. In this study, 17 putative endolysins were identified from bacteriophages infecting X. arboricola pv. juglandis and P. syringae pv. syringae. Based on conserved domain analyses, 12 were classified as glycosidases, four as amidases, and one as an endopeptidase. From these, a recombinant amidase (LysP) and a recombinant glycosidase (LysX) were expressed in E. coli, purified, and evaluated as pure enzymes. Both endolysins exhibited significant antimicrobial activity, reducing P. syringae pv. syringae viability by 62–78.3% and X. arboricola pv. juglandis viability by 51.5–53.1%, respectively. These findings highlight these recombinant endolysins as promising candidates for the development of biocontrol strategies against bacterial plant pathogens.