Exploring Outer Membrane Dynamics and Optimising Phage Isolation inVeillonella parvula

Abstract

The understanding of evolutionary transition between diderm and monoderm bacteria remains incomplete. Veillonella parvula, a diderm member of the monoderm-dominated Firmicutes phylum, offers a unique model for investigating this shift. Unlike classical diderms, V. parvula possesses a reduced set of outer membrane (OM) tethering proteins. Previous studies have shown that deletion of genes such as ompM compromises OM integrity, while additional deletion of tamB can restore it and alter the essentiality of other genes. This thesis focuses on bamA, a gene considered essential in most diderms. The project aimed to assess bamA’s role in both wild-type and ΔompM ΔtamB genetic contexts by integrating an inducible bamA construct and assembling deletion tools. The inducible system was successfully inserted into the genome, and the deletion constructs were completed. In parallel, a protocol was developed for the isolation of bacteriophages infecting V. parvula. Although no phages were identified during this work, the optimized protocol offers a practical framework for future phage discovery in non-model, anaerobic organisms. Together, these tools contribute to expanding the genetic and methodological toolkit for studying envelope evolution in diderm Firmicutes.