Stability of rcsC11 mutant of Salmonella Typhimurium under different growth conditions

TORRES, M.A; LECCESSE TERRAF MC; PESCARETTI MM,; MINHAK, C. J; DELGADO MA

Mar del Plata

Congreso; 51th Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2015

SAIB

STABILITY OF RcsC11 MUTANT OF Salmonella typhimurium UNDER DIFFERENTGROWTH CONDITIONSTorres, MA; Leccesse Terraf, MC; Pescaretti, MM; Minahk, CJ; Delgado, MA.Instituto Superior de Investigaciones Biológicas. E-mail: mtorres@fbqf.unt.edu.arSalmonella is a great prevalence pathogen in the population of Argentina. Its infection depends on the modulation ofthe pathogenicity islands genes expression, controlled by different regulatory systems. The RcsCDB system regulatesthe biosynthesis of colanic acid and flagella, and the virulence genes, among others. In the rcsC11 mutant the systemis constitutively active, resulting in a mucoid phenotype and attenuated virulence. The aim of this study was toinvestigate the stability of the rcsC11 point mutation under different conditions that simulate the host environment,which was evaluated by the viability and reversion of mucoid phenotype. Our results demonstrated that, of all testedconditions, only the acid condition modified the rcsC11 mucoid phenotype. In addition, such reversion was observedafter the fifth sub-culture at pH 4.5. To confirm the phenotype reversion, mucoid and "non mucoid" colonies weretransduced with a chromosomal lacZ fusion to the RcsB-reporter flhC gene. Our results demonstrated that ?nonmucoid? colonies displayed similar β-galactosidase activity levels than the wild type strain, supporting that thercsC11 point mutation was reverted in all of them. Even so, our results suggest that the rcsC11 strain is an excellentcandidate for the attenuate vaccines development, because the mucoid phenotype reversion was detected only in laterstages of the assay.