Aeoliella straminimaris sp. nov., a novel member of the phylum Planctomycetota with an unusual filamentous structure

Organisms with distinctive biological features and cellular organization constitute the bacterial phylum . In this study, we formally describe a novel isolate, strain ICT_H6.2 , isolated from sediment samples collected in the brackish environment of the Tagus River estuary (Portugal) using an iChip-based culturing technique. The 16S rRNA gene analysis placed this strain into the phylum and family , with a similarity value of 98.0 % to its closest relative Pan181 , the currently only known member of the genus. Strain ICT_H6.2 has a genome size of 7.8 Mbp and a DNA G+C content of 59.6 mol %. Strain ICT_H6.2 is heterotrophic, aerobic and capable of microaerobic growth. This strain grows from 10 to 37 °C and from pH 6.5 to 10.0, requires salt to grow, and can tolerate up to 4 % (w/v) NaCl. Diverse nitrogen and carbon sources are utilized for growth. Morphologically, strain ICT_H6.2 is white to beige pigmented, spherical to ovoid in shape and around 1.4×1.1 µm in size. The strain clusters mainly in aggregates and younger cells show motility. Ultrastructural studies showed a cell plan with cytoplasmatic membrane invaginations and unusual filamentous structures with hexagonal organization in transversal section. Morphological, physiological and genomic comparison between strain ICT_H6.2 and its closest relatives strongly suggests it represents a novel species within the genus , for which we propose the name sp. nov., represented by strain ICT_H6.2 as the type strain (=CECT 30574 =DSM 114064 ).