Response of Chromobacterium violaceum to the oxidant hypochlorous acid

• Grant number: 25/12667-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2025
• End date: August 31, 2027
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: José Freire da Silva Neto
• Grantee: Carolina Panosso Schuindt
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 21/06894-0 - Bacterial transcription factors involved in metal homeostasis, oxidative stress and virulence: investigating how Chromobacterium violaceum switches from the environment to the host, AP.JP2

Abstract

Reactive chlorine species (RCS), such as hypochlorous acid (HOCl), are potent oxidants found in disinfectants and produced by immune cells as part of the antimicrobial defense. Bacteria have evolved various defence mechanisms against RCS. The response to HOCl in Chromobacterium violaceum, an environmental bacterium that interacts with neutrophils and other immune cells during infection in mammalian hosts, remains unknown. The aim of this project is to uncover the adaptive response and resistance mechanisms to HOCl in C. violaceum, as well as investigating how these responses impact the virulence of this pathogen. Growth curves and survival assays will be employed to evaluate C. violaceum's resistance to HOCl. RNA sequencing (RNA-seq) will be used to identify the repertoire of genes whose expression is altered in response to HOCl. Genes that are upregulated upon HOCl exposure and that encode transcription factors or antioxidant enzyme systems will be selected for mutant generation. These mutants will then be characterised for their susceptibility to HOCl in vitro and in cell culture, as well as in vivo using an animal model. The data generated by this project will improve our understanding of bacterial defence mechanisms against hypochlorous acid. (AU)