Tailocins in action: defence strategie of rhizospheric Pseudomonas

FERNANDEZ, M.; GODINO, A.; PRÍNCIPE, A.; MORALES, G.M; FISCHER, S.E.

La Plata

Workshop; Imaging techniques for biotechnological and biomedical applications; 2016

Bacteriocins are protein produced by bacteria that can kill closely related species to the producer. P. aeruginosa synthetizes three types of pyocins that differ in their morphology and killing mode: R, F (phage tail-like bacteriocins) and S (soluble proteins) -type pyocins (Ghequire and De Mot, 2014). P. fluorescens SF4c is a plant-growth promoting bacterium that produces phage-like pyocins (tailocins), which inhibit the growth of the phytopathogenic strain Xanthomonas axonopodis pv vesicatoria Xcv Bv5-4a (Fischer et al., 2012). The aim of this work was to elucidate the action mode of the tailocins secreted by the strain SF4c. The structure of the tailocin was visualized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Action mechanism of the tailocins on the strains X. axonopodis pv vesicatoria Xcv Bv5-4a and P. protegens CHA0 was studied by atomic force microscopy (AFM). The pyocins presented a structure similar to the bacteriophage tails and they were attached to the surface cell Xcv Bv5-4a to exert their antimicrobial action. The tailocins action was evidenced in the AFM images as a decrease in the cell height of strain Xcv Bv5-4a. These results suggest that the action mechanism of these pyocins involve the damage of the membrane of susceptive cells, probably by formation of pores and then, a loss of intracellular material. In contrast, the tailocins have not effect on strain CHA0. The characterization of this class of antimicrobial compounds is relevant for their potential application as biocontrol agent.