Exploring phage-bacteria interactions of Vibrio metschnikovii in the aging gut microbiome of African turquoise killifish

The African turquoise killifish undergoes rapid aging-associated changes in its gut microbiome, including an enrichment of Vibrio in old fishes. Among these bacteria, Vibrio metschnikovii provides a suitable model to study how phage–bacteria interactions are shaped by host aging and how they may influence microbial community dynamics. This project focuses on the interaction between V. metschnikovii isolates from young and old killifish and the lytic phage VmL. Initial phage susceptibility assays revealed a clear age-associated pattern: many old-fish-derived isolates are susceptible to VmL, whereas young-fish-derived isolates are largely resistant. This suggests that aging-associated V. metschnikovii populations differ in the mechanisms determining phage host range and bacterial survival. The overall aim of this project is to identify the bacterial factors underlying this difference in phage susceptibility and to assess whether phages can be used as targeted tools to perturb microbial communities. To this end, the project combines bioinformatic analysis, phage biology, molecular biology, genetic engineering and GFP-based mixed-community experiments. This approach will help to understand how receptor diversity, bacterial defense mechanisms and community context shape phage–bacteria interactions in the aging gut microbiome.

PhD start: 03/01/2025