Planctoellipticum variicoloris gen. nov., sp. nov., a novel member of the family Planctomycetaceae isolated from wastewater of the aeration lagoon of a sugar processing plant in Northern Germany.

In the present study, we characterise a strain isolated from the wastewater aeration lagoon of a sugar processing plant in Schleswig (Northern Germany) by Heinz Schlesner. As a pioneer in planctomycetal research, he isolated numerous strains belonging to the phylum Planctomycetota from aquatic habitats around the world. Phylogenetic analyses show that strain SH412 belongs to the family Planctomycetaceae and shares with 91.6% the highest 16S rRNA gene sequence similarity with Planctopirus limnophila DSM 3776. Its genome has a length of 7.3 Mb and a G + C content of 63.6%. Optimal growth of strain SH412 occurs at pH 7.0-7.5 and 28 °C with its pigmentation depending on sunlight exposure. Strain SH412 reproduces by polar asymmetric division ("budding") and forms ovoid cells. The cell size determination was performed using a semi-automatic pipeline, which we first evaluated with the model species P. limnophila and then applied to strain SH412. Furthermore, the data acquired during time-lapse analyses suggests a lifestyle switch from flagellated daughter cells to non-flagellated mother cells in the subsequent cycle. Based on our data, we suggest that strain SH412 represents a novel species within a novel genus, for which we propose the name Planctoellipticum variicoloris gen. nov., sp. nov., with strain SH412 (= CECT 30430 = STH00996, the STH number refers to the Jena Microbial Resource Collection JMRC) as the type strain of the new species.