Description of the novel planctomycetal genus Bremerella, containing Bremerella volcania sp. nov., isolated from an active volcanic site, and reclassification of Blastopirellula cremea as Bremerella cremea comb. nov.

Planctomycetes are part of the PVC superphylum together with Verrucomicrobia, Chlamydiae and others. They are budding bacteria with very distinctive characteristics, such as a remarkable morphology and cell biology. Planctomycetes can be found in almost all habitats, and seem to have a preference for marine biotic and abiotic surfaces, on which they frequently occur in biofilm-forming communities. To extend the number of axenic cultures of planctomycetal strains, we isolated Pan97 from a biofilm in a volcanic site close to the Italian island Panarea in the Thyrrhenian Sea. The physiology, genome and morphology of the novel strain were characterised revealing typical planctomycetal characteristics, such as, division by polar budding and presence of crateriform structures. The strain shows pear-shaped cells of 1.5 ± 0.3 µm × 0.8 ± 0.2 µm and forms white- to cream-coloured colonies on solid medium. Strain Pan97 is mesophilic and neutrophilic, since growth was observed  at a pH range of 5.5-9.5 with optimal growth at pH 7.0 and at a temperature range of 15-40 °C with a maximal growth rate at 36 °C. Pan97 has a genome size of 6,496,182 bp with a G + C content of 56.2%. 5264 protein-coding genes were identified, of which 2141 genes (41%) encode hypothetical proteins. Based on the phylogenetic analysis, we suggest that Pan97 (DSM 101992 = LMG 29460) represents a novel species of a novel genus within the family Planctomycetaceae, for which we propose the name Bremerella gen. nov., with strain Pan97 classified as Bremerella volcania sp. nov. Based on our analysis, we also propose the reclassification of Blastopirellula cremea Lee et al. 2013 as Bremerella cremea comb. nov., as this species is considered to be the type species of the novel genus Bremerella.