Salmonella BIOFILMS: PARTICIPATION OF THE RCSCDB REGULATORY SYSTEM

PÁEZ PAZ INDIANA DE MARÍA; LECCESE TERRAF MARÍA CECILIA; PESCARETTI MARÍA DE LAS MERCEDES; DELGADO MÓNICA ALEJANDRA

Encuentro; IV Reunión Conjunta de Sociedades de Biología de la República Argentina; 2020

Bacterial biofilms are complex communities consisting of microorganisms embedded in a self-produced extracellular matrix. Salmonella is able to form biofilm on the surface of the gallstones that produce the persistence of the bacterial colonization in the carrier patients. The RcsCDB phosphorelay system has an important role in the bacterial physiology, mainly in the response to extracytoplasmic stress signaling. It was shown that the factors affecting the cell envelope leads to the activation of the system and consequently the modulation of capsule synthesis, motility behavior and biofilm formation. Previously, in our laboratory we characterize the rcsC11 mutant, in which RcsCDB constitutive activation happens, as a not virulent strain that can be used as an attenuated vaccine. We here investigated whether the RcsCDB system activation conditions have the ability to affect the red dry/rough (RDAR) morphotype and the levels of biofilm formation on polystyrene plates, distinctive of Salmonella. For this purpose, we used the 14028s wild type strain harboring the prcsB plasmid, and the tolB and rcsC11 mutants as RcsCDB system activation conditions. In addition, we compared the ability of biofilm formation of the attenuated mutant respect to the wild-type strain on uniform gallstones mainly composed of cholesterol, removed from a single lithiasic patient. To this end, gallstones were incubated in LB medium without salt, supplemented or not with bile salts, previously inoculated with wild type and rcsC11 Salmonella strains. After 7 days, the biofilm formed was evaluated by scanning electron microscopy. Our results demonstrated that the RcsCDB system activation negatively affects the Salmonella biofilm development. In addition, our findings on the inability of the rcsC11 strain to form biofilms supports that this mutant is an excellent candidate for the development of attenuated vaccines.