Microfluidic Investigation of Myeloid-derived Oxidants in Salmonella Adaptation

During infection, neutrophils unleash an oxidative burst, flooding the phagosome with a battery of highly reactive oxidants. Crucially, the species thought to mediate microbial killing are extremely transient - reacting within microseconds and diffusing only nanometres before vanishing. These features make them perfectly suited to deliver lethal damage locally while limiting collateral injury to host tissues. Yet the very properties that confer their biological efficacy - short lifetime, extreme reactivity, and spatial confinement - also render them technically inaccessible. In conventional microbiological assays, they decay within seconds or are scavenged by culture media, making sustained and controlled exposure virtually impossible. As a result, we still lack a clear understanding of how these oxidants injure bacterial cells. I have recently developed a continuous-flow microfluidic platform that couples photosensitisation, redox chemistry, and live-cell imaging to generate and maintain defined fluxes of unstable oxidants. This approach revealed previously hidden phenotypes induced by urate-derived oxidants, demonstrating the transformative potential of controlling short-lived species at the single-cell level. MIMOSA will generalise this strategy to the broader set of oxidants generated during the neutrophil burst, including superoxide and hypochlorous acid. By integrating microfluidic control with genetic dissection, experimental evolution and quantitative phenotyping, I will chart the molecular damage, regulatory responses, and adaptive strategies that the human pathogen Salmonella enterica serovar Typhimurium deploys under oxidative attack. This dual advance - technological innovation and mechanistic exploration - will establish a robust workflow for studying the biology of short-lived oxidants. MIMOSA will uncover fundamental principles of bacterial survival under oxidative stress and reshape our understanding of how the immune system controls infection.