How does low-temperature plasma damage the bacterial outer membrane?

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Global challenges include microbial infections, and bacterial contamination ofsurfaces (e.g. food) and the environment. With resistance to antibiotics anincreasing concern alternative approaches need to be developed. One of theseis low-temperature plasma (LTP). A mix of biologically active reactive oxygenand nitrogen species are formed when high voltage is applied to a gas flow. Thechemical properties of atmospheric pressure LTP offers great promise as anantibiotic-free therapeutic for combating topical bacterial infection associatedwith wounds and skin ulcers, and are another potential weapon in our arsenalto combat antimicrobial resistance (AMR). However, there are key biologicaland physical questions remaining that need to be addressed to enhance thedevelopment of LTP for use in society. For example, the physical mechanismwhereby the reactive species in LTP damage the bacterial envelope and rendera cell non-viable is very poorly understood (e.g. Are pores formed in themembrane?). To further develop and optimise the use of LTP, a greaterunderstanding of the cellular mechanisms of its bactericidal effects is required,and this will be the focus of this project.Our current understanding of how LTP affects microbes is largely based onpopulation-level cell viability assays or single-cell imaging techniques with poortemporal resolution due to the need for extensive sample preparation prior toimaging. By combining our expertise in real-time single-cell fluorescenceimaging (CGB), LTP generation (DO'C), and bacterial phenotyping acrossdifferent time and length scales (MvdW), significant strides forward can bemade in understanding how plasma treatment alters the membrane bilayerboth in vivo and in vitro. This knowledge will feed into ongoing work in the YorkPlasma Institute that focuses on characterising and manipulating thecomposition of the reactive species in plasma to enhance biological activity.This project will investigate how different LTPs affect the cell envelope of Gramnegative bacterial strains with different cell surfaces by using a single-cell levelapproach. The student will exploit methods for fluorescently-labelling OMPsand LPS to monitor morphological changes in the cell envelope during and afterexposure to LTP. Single-cell imaging will be done using advanced multi-colourfluorescence microscopy methods and novel technology developed to allowsimultaneous exposure to different types and dosages of LTP. Time-lapse cellimaging after exposure to LTP will be done to determine if any morphologicaldifferences can be observed, and to identify potential phenotypic traits of non-viable cells and viable persister cells. Knowledge gained from this project will beused to develop a mechanistic model of LTP-induced membrane damage andidentify potential agents that could be used to enhance the damaging effect ofplasma on Gram negative bacteria.This project will provide excellent specialised training in cutting-edge single-cellanalytical methods combined with a good understanding of membrane biologyand microbiology. Professional skills training will be provided by the White RoseDTP. The student will also improve their professional skills by attending thesupervisors' lab meetings, departmental seminars and research conferences,and participating in outreach activities. The student will join a vibrant cross-disciplinary community of PhD students.This project is suitable for an applicant with a strong background in physics andchemistry, and a keen interest in understanding biological processes at themolecular level and participating in the development of novel antibacterialapproaches.