The novel taxon Lacunimicrobium album gen. nov., sp. nov. is constituted by three planctomycetotal strains isolated from freshwater habitats in Northern Germany

The majority of characterized members of the phylum Planctomycetota were isolated from marine habitats. To expand the open collection of limnic planctomycetes, we here characterize three isolates from the strain collection of Heinz Schlesner (Kiel University), a pioneer in the research on budding planctomycetes and other bacteria with uncommon morphologies. The three strains SH203, SH248^Tand SH280 were isolated from two municipal ponds in Kiel and from a nature reserve close to a gypsum mine in the surroundings of Hamburg, Northern Germany. The three isolates share an identical 16S rRNA gene sequence over the analyzed sequence of ca. 1300 bp. Cells are pear-shaped, motile, non-pigmented and show the typical asymmetrical division mode through polar budding observed in most other members of the family Planctomycetaceae. Phylogenetic analyses identified the three described species of the genus Rubinisphaera as the current closest relatives. The comparison of five phylogenetic markers along with differences in phenotypic and genomic features together delineate the novel strains from the genus Rubinisphaera. Hence, we introduce Lacunimicrobium album gen. nov., sp. nov., a novel taxon in the family Planctomycetaceae. The novel species is represented by the type strain SH248^T(= CECT 30703^T = STH01007^T; the STH number refers to the Jena Microbial Resource Collection JMRC). It has a heterotrophic, mesophilic and neutrophilic profile and a genome with a length of 5.42 Mbp and a DNA G + C content of 54.6%.