essential genome and the divergence of cell division in the PVC superphylum.

The -- superphylum comprises bacteria with divergent traits, epitomizing the vast biodiversity of non-model organisms that remains unexplored. Among its members, and exhibit unique adaptations, including variations in peptidoglycan structure and cell division without FtsZ. represents the only name-giving phylum within the PVC not extensively investigated. Here, exhaustive transposon mutagenesis combined with massive sequencing reveal the essential genome of . The essentiality report demonstrates that the cluster is essential except . Additionally, peptidoglycan analysis evidences that the composition and saccular arrangement are canonical, contrarily to and Targeted mutagenesis for was also developed, thus reinforcing its status as a model for . Ultimately, the evolutionary divergences of the cluster in PVC, combined with the previous results, suggest that its Last Common Ancestor was a Gracilicutes-like bacterium dividing by an FtsZ-mediated binary fission with peptidoglycan, from which current phyla diverged.