Effect of a Pseudomonas fluorescens tailocin against phytopathogenic Xanthomonas observed by atomic force microscopy

- The effect of a phage tail-like bacteriocin from P. fluorescens is analyzed through AFM.
- Tailocins inhibit the growth of the phytopathogenic Xanthomonas axonopodis pv. vesicatoria strain.
- Tailocins adhere to the cell wall of X. axonopodis pv. vesicatoria.
- Tailocins damage the cellular envelope of phytopathogenic bacteria.
- Tailocins could be used in the future as biocontrol agents.

Phage tail-like bacteriocins, called tailocins, represent a class of protein complexes produced by a multitude of bacteria. Pseudomonas fluorescens SF4c, a strain isolated from wheat rhizosphere, produces a bacteriocin similar to phage tail-like pyocins of Pseudomonas aeruginosa. This tailocin has antimicrobial activity against several phytopathogenic strains of the genus Xanthomonas and Pseudomonas. In this work, the effect of the SF4c tailocin on the phytopathogenic strain X. axonopodis pv vesicatoria Xcv Bv5-4a was analyzed through Atomic Force Microscopy (AFM). We demonstrated that tailocins adhere and cause damage to the cell envelope of strain Xcv Bv5-4a. This results in a rapid leakage of intracellular materials, with the subsequent decrease of cell volume. Finally, lysis of sensitive bacteria occurs. This study provides, to our knowledge, the first evidence about the effect of a tailocin analyzed by AFM. Further studies are in progress to evaluate the use of SF4c tailocin in the biocontrol of bacterial spot on tomato.