Schlesneria sphaerica sp. nov., a neutrophilic, xylan-degrading planctomycete from a mountain wetland, and emended description of the genus Schlesneria.

Aerobic chemoorganotrophic planctomycetes of the genus Schlesneria colonize a wide spectrum of freshwater ecosystems. The only described species of this genus, S. paludicola, is represented by ellipsoid-shaped, moderately acidophilic bacteria isolated from acidic peat bogs. Here, we characterize a novel neutrophilic member of this genus from a mountain wetland, strain T3-172T. This isolate possesses unpigmented, non-motile, spherical cells, which grow on media containing some mono- and polysaccharides in the pH range of 6.0-7.5 and at temperatures between 15 and 37°C. Good growth is observed on xylan, one of the major plant cell wall biopolymers. The genome of strain T3-172T is 7.16 Mb in size and contains two unlinked sets of rRNA genes, 93 tRNA genes, and about 5500 potential protein-coding genes. Among the latter, the GH5 family protein is identified as the most reliable candidate for the cleavage of xylan. The 16S rRNA gene sequence of strain T3-172T displays 97.8% similarity to that of S. paludicola MPL7T, and the average nucleotide identity between the genomes of these planctomycetes is 71.6%. We, therefore, propose a novel species of the genus Schlesneria, S. sphaerica sp. nov., with strain T3-172T (=KCTC 102306T = VKM B-3856T) as the type strain.