The evolution of aerotolerance and aerobic growth in Campylobacter jejuni

Campylobacter jejuni (C. jejuni) is an enteric zoonotic pathogen that is one of the most common causes of gastroenteritis worldwide. Whilst C. jejuni infection is typically self-limiting in more affluent countries, it exerts a more significant burden in lower to middle-income countries (LMICs) due to chronic reinfection. C. jejuni colonises the guts of animals including chickens, cattle, and wild birds; and is transmitted via the consumption of undercooked meats and contaminated water sources. Due to the vast array of hosts and reservoirs C. jejuni occupies it is important to understand how C. jejuni spreads through a community and more specifically to understand survival and tolerance to environmental stressors within these transmission networks.
The overall aim of this work is to understand C. jejuni response to environmental stressors that may contribute to the transmission of diarrhoeal disease in LMICs. This project will utilise isolates from sampling in The Gambia, Burkina Faso, and Ghana as part of a multi-university study called 'GetCampy Africa'. This will be achieved by the development of high-throughput protocols to assess C. jejuni phenotypes and genotypes responsible for tolerance to stressors, such as oxygen, antibiotics, and detergents. Results from these will inform experiments where I will evolve isolates under aerobic stress and identify adaptive mutations that confer aerotolerance. With the end goal of providing better resolution to, and understanding of, adaptive features that increase the transmissibility of C. jejuni that will ultimately inform transmission networks mapped from the larger 'GetCampy Africa' project.
Objective 1: Optimise high-throughput growth and phenotypic characterization assays using lab reference and European C. jejuni strains. This method will form the basis of other protocols to assess the impact of environmental stressors on larger sets of C. jejuni
Objective 2: Phenotyping and sequencing of C. jejuni strains isolated from the 'GetCampy Africa' Project. Using the methods developed in objective 1 assess variance in aerotolerance and aerobic growth to identify host and/or lineage-specific differences and similarities.
Objective 3: Using experimental evolution to identify genes under selection for aerotolerance. Throughout the project evolution experiments will be run with control lines and experimental lines exposed to different environmental stressors- initially focussing on aerobic stress. Ancestral and evolved lines will be sequenced to identify genes that confer aerotolerance and compare them to mutations seen in natural populations identified from genome-wide association studies.
Objective 4: Molecular engineering of lab reference strain and natural isolates. Candidate genes identified in objective 3 will be knocked 'in' or 'out' from lab strains to allow phenotypic analysis to quantify the impacts on aerotolerance.