Conjugative-killer plasmids, a novel antimicrobial alternative

Targeted killing of pathogenic bacteria without harming beneficial members of the host microbiota holds promise as a strategy to cure disease and limit both imbalances in the microbiota and development of antimicrobial resistance. Recent work from the Unit de Plasticit du Gnome Bactrien has demonstrated that genetic modules based on toxin-intein systems delivered by conjugation are highly effective antimicrobials agents, able to selectively kill Vibrio cholerae in mixed populations. In this line of work, the project described in this proposal aims at adapting the aforementioned system to other pathogens of clinical importance (Salmonella spp. Shigella spp and Klebsiella pneumoniae) by including new toxin modules whose expression depends on transcriptional factors that are exclusively present in the targeted bacteria. Additionally, to ensure an efficient dissemination and maintenance across the microbial gut population, we intent to engineer conjugative plasmids to be transferred and maintained between Enterobacteriaceae and Bacteroides, one of the main constituents of the gut microbiome. Once validated under laboratory conditions, the system will be assayed in a Caernorhabditis elegans model, either with the aim of eliminating a specific pathogen causing disease or as a probiotic agent against pathogenic colonization. The results obtained from these preliminary tests will direct the refinements needed for the generation of an effective tool against antimicrobial resistant pathogens in a real scenario.