Kolteria novifilia, a novel planctomycetotal strain from the volcanic habitat of Panarea divides by unusual lateral budding.

Members of the phylum Planctomycetota are ubiquitous bacteria that play important roles in the global carbon and nitrogen cycle. In this study, we sampled the shallow-sea hydrothermal vent system close to Panarea Island, Italy, and analyzed the bacterial diversity in this habitat using a cultivation-independent amplicon sequencing approach. Motivated by the observed abundance of members of the phylum Planctomycetota, we employed cultivation conditions that facilitate the enrichment of planctomycetes and isolated strain Pan216T. This strain shows a rarely observed type of cell division-lateral budding. Based on 16S rRNA gene- and multi-locus sequence analyses, its phylogenetic position in the phylum Planctomycetota appears vague. Strain Pan216T clustered between the different described families in the class Planctomycetia. The novel isolate shares the highest sequence identity (85.4%) of the 16S rRNA gene with Thermostilla marina SVX8T, indicating that this strain belongs to a novel family. In addition to its uncommon cell division mode, Pan216T cells are pill-shaped and covered by a putative outer surface layer. Genomic analyses of strain Pan216T revealed many giant genes, putative S-layer protein-encoding genes, and only a limited set of canonical cell division genes. Based on the results of the polyphasic analysis, we conclude that strain Pan216T constitutes a novel family within the phylum Planctomycetota, for which we propose the name Kolteriaceae fam. nov. The novel species Kolteria novifilia gen. nov., sp. nov. is represented by the type strain Pan216T (= DSM 100414T = CECT 9536T).