Stress response and virulence of Vibrio vulnificus: role of the stressosome and secondary effects of antibiotic resistance
Cutugno, Laura
Cutugno, Laura
Loading...
Publication Date
2021-12-22
Type
Thesis
Downloads
Citation
Abstract
Bacterial stress response and virulence are two key factors that guarantee the survival and propagation of pathogens. The elucidation of factors that affect these aspects in the human pathogen Vibrio vulnificus was the focus of this thesis. In particular, the role of the stressosome and the pleiotropic effects of antibiotic resistance were investigated. The stressosome is a widely distributed complex that has been found to sense and integrate environmental stress signals and modulate the bacterial stress response in Gram-positive bacteria. The genetic locus encoding the stressosome proteins has been found in several bacterial species including V. vulnificus. The variability of the putative regulatory outputs and sensory domains is very intriguing and delineates the profile of a complex that has evolved to modulate a wide range of responses with effects on different aspects of bacterial physiology. Here, we demonstrated that the stressosome in V. vulnificus reshapes the bacterial metabolism and motility during growth in Chemically Defined Media, most likely through regulation of c-di-GMP. This represents the first in vivo characterisation of the role of the stressosome in a Gram-negative bacterium. Antibiotic resistance constitutes a concerning issue that threatens health and economy worldwide. The secondary effects of rifampicin resistance in V. vulnificus were elucidated for the first time in this thesis. Various and unpredictable secondary effects on growth, stress response and virulence were observed and compared to previously-reported effects in other microorganisms. These findings have the potential to be used as a tool to predict the diffusion, in the environment and the host, of the mutations conferring resistance. Moreover, we showed that some of the effects reported have relevant consequences on commonly used research and diagnostic protocols. Overall, this thesis contributed to expanding the knowledge on previously-unexplored aspects of the stress response and virulence of a deadly human pathogen.
Publisher
NUI Galway