Stieleria sedimenti sp. nov., a Novel Member of the Family Pirellulaceae with Antimicrobial Activity Isolated in Portugal from Brackish Sediments

The phylum Planctomycetota is known for having uncommon biological features. Recently, biotechnological applications of its members have started to be explored, namely in the genus Stieleria. Here, we formally describe a novel Stieleria isolate designated as strain ICT_E10.1(T), obtained from sediments collected in the Tagus estuary (Portugal). Strain ICT_E10.1(T) is pink-pigmented, spherical to ovoid in shape, and 1.7 µm ± 0.3 x 1.4 µm ± 0.3 in size. Cells cluster strongly in aggregates or small chains, divide by budding, and have prominent fimbriae. Strain ICT_E10.1(T) is heterotrophic and aerobic. Growth occurs from 20 to 30 °C, from 0.5 to 3% (w/v) NaCl, and from pH 6.5 to 11.0. The analysis of the 16S rRNA gene sequence placed strain ICT_E10.1(T) into the genus Stieleria with Stieleria neptunia Enr13(T) as the closest validly described relative. The genome size is 9,813,311 bp and the DNA G+C content is 58.8 mol%. Morphological, physiological, and genomic analyses support the separation of this strain into a novel species, for which we propose the name Stieleria sedimenti represented by strain ICT_E10.1(T) as the type of strain (=CECT 30514(T)= DSM 113784(T)). Furthermore, this isolate showed biotechnological potential by displaying relevant biosynthetic gene clusters and potent activity against Staphylococcus aureus.