Effect of RpoS on tolerance and persistence in natural Escherichia coli isolates

• Grant number: 22/00100-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2022
• End date: December 31, 2022
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Beny Spira
• Grantee: Felipe de Moraes Gomes
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Recent studies point to the existence of several genes, molecules, and mechanisms involved in antibiotic tolerance and persistence in bacteria, among these genes we have what encodes the RpoS protein. RpoS is an RNA polymerase sigma factor that it acts as a central regulator of genes induced in the stationary phase and also as a master regulator of general stress response under various conditions, including its regulation in virulence genes, biofilm, etc. Our laboratory characterized the level and the RpoS status of more than 300 environmental strains of Escherichia coli, which showed different RpoS profiles. Antibiotic tolerance is the ability to transiently survive exposure to high concentrations of an antibiotic. Peron the other hand, persistence refers to a small subpopulation of bacterial cells, within a sensitive population, who are generally quiescent and capable of surviving high concentrations of antibiotics. The literature in the area presents results conflicting about the effect of RpoS on tolerance/persistence to various antibiotics, and most of these studies were performed with laboratory strains of E. coli, in this project, the tolerance/persistence profile of 20 strains will be analyzed. Of this collection, is in relation to beta-lactam antibiotics (ampicillin), aminoglycosides (kanamycin), and quinolones (ciprofloxacin). For this, strains with high RpoS level will have the rpoS deleted, while strains that present null expression or low RpoS will be transformed with rpoS+ plasmids to increase the expression of this protein. Recombinant bacteria will be tested for tolerance/persistence to antibiotics mentioned in death curve experiments. In this way, we hope to determine whether RpoS has a role in tolerance/persistence to antibiotics in natural E. coli isolates, which are more relevant than strains of the laboratory from an environmental point of view, mainly in relation to the E. coli response to the presence of antibiotics in nature.(AU)