IMIS - Marine Onderzoeksgroepen

Planctomycetes of the family Pirellulaceae are commonly addressed as budding aquatic bacteria with a complex lifestyle. Although this family is well represented by cultured and taxonomically characterized isolates, nearly all of them were obtained from brackish or marine habitats. The examples of described freshwater Pirellulaceae planctomycetes arelimited to two species only, Pirellula staley and ‘ Anatilimnocola aggregata’. In this study, we characterized a novel freshwater planctomycete of the genus ‘Anatilimnocola’, strain PX40^T, which was isolated from a boreal eutrophic lake. Strain PX40^T was represented by budding, unpigmented, ellipsoidal to pear-shaped cells, which often occurred in characteristic flower-like rosettes. Cells were covered by bundles of fimbriae; crateriform-like structures were localized on a reproductive cell pole only. These planctomycetes were obligately aerobic, heterotrophic bacteria that utilized various sugars and some polysaccharides, and were highly sensitive to NaCl. Growth occurred in the pH range 5.0–7.5 (with an optimum at pH 6.5–7.0), and at temperatures between 15 and 30 °C (with an optimum at22–25 °C). The major fatty acids of strain PX40^T were C18:1 ω9c, C16:0, and 16:1ω7c; cells also contained a wide variety of hydroxy- and dihydroxy-fatty acids and a C31:9 alkene. The major intact polar lipids were diacylglyceryl-(N,N,N)-trimethylhomoserines. The 16S rRNA gene sequence of strain PX40^T displayed 96.6%similarity to that of ‘Anatilimnocola aggregata’ ETA_A8 ^T. The genome of strain PX40^T was 8.93 Mb in size and contained one copy of rRNA operon, 76 tRNA genes and 7092 potential protein-coding genes. The DNA G+C content was 57.8%. The ANI value betweenstrain PX40^T and ‘Anatilimnocola aggregata’ ETA_A8 ^T was 78.3%, suggesting that these planctomycetes representdistinct species. We, therefore, propose a novel species of the genus ‘ Anatilimnocola’, ‘A. floriformis’ sp. nov., with strain PX40^T (= KCTC 92369^T = VKM B-3621^T = UQM 41463^T) as the type strain.