Stability of the Salmonella Typhimurium rcsC11 mutant under different stress conditions

TORRES, M.A; LECCESE, MC; MINHAK, C. J; DELGADO M. A

MICROBIOLOGY-UK

SOC GENERAL MICROBIOLOGY

Lugar: London; Año: 2019

1350-0872

The virulence genes of Salmonella are modulated during infection by several regulatory systems, one of the most important is the RcsCDB system. The S. Typhimurium rcsC11 strain harbors the rcsC11 point mutation, displaying a constitutive activation of this system, which is characterized by mucoid colonies and attenuated virulence phenotypes. In this work, the stability of rcsC11 mutation was analyzed under stress conditions. Under acid and anaerobic stresses, we observed the appearance of small and non-mucoid colonies of the rcsC11 strain. The sequencing of the rcsC gene from these colonies showed that the mutation is conserved. Moreover, we found that small colonies were also generated when the wild type strain grew in acid and anaerobic conditions. It is worth to note that the transition from normal to atypical colonies of both strains only took place after several days of incubation and was not observed during eukaryotic cells infection. Therefore, the appearance of these atypical colonies is a characteristic feature of S. Typhimurium strains under stressful situations and does not involve a reversion of the rcsC11 allele nor implies any risk to mammalian cells. Therefore, we propose that S. Typhimurium rcsC11 strain is a good candidate for the development of attenuated vaccines