title: Niches of two polysaccharide-degrading Polaribacter isolates from the North Sea during a spring diatom bloom.
abstract: Members of the flavobacterial genus Polaribacter thrive in response to North Sea spring phytoplankton blooms. We analyzed two respective Polaribacter species by whole genome sequencing, comparative genomics, substrate tests and proteomics. Both can degrade algal polysaccharides but occupy distinct niches. The liquid culture isolate Polaribacter sp. strain Hel1_33_49 has a 3.0-Mbp genome with an overall peptidase:CAZyme ratio of 1.37, four putative polysaccharide utilization loci (PULs) and features proteorhodopsin, whereas the agar plate isolate Polaribacter sp. strain Hel1_85 has a 3.9-Mbp genome with an even peptidase:CAZyme ratio, eight PULs, a mannitol dehydrogenase for decomposing algal mannitol-capped polysaccharides but no proteorhodopsin. Unlike other sequenced Polaribacter species, both isolates have larger sulfatase-rich PULs, supporting earlier assumptions that Polaribacter take part in the decomposition of sulfated polysaccharides. Both strains grow on algal laminarin and the sulfated polysaccharide chondroitin sulfate. For strain Hel1_33_49, we identified by proteomics (i) a laminarin-induced PUL, (ii) chondroitin sulfate-induced CAZymes and (iii) a chondroitin-induced operon that likely enables chondroitin sulfate recognition. These and other data suggest that strain Hel1_33_49 is a planktonic flavobacterium feeding on proteins and a small subset of algal polysaccharides, while the more versatile strain Hel1_85 can decompose a broader spectrum of polysaccharides and likely associates with algae.
authors.affiliation: 1] Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany [2] State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Xing
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hahnke
authors.affiliation: 1] Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany [2] Institute of Marine Biotechnology e.V., Greifswald, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Unfried
authors.affiliation: Institute of Marine Biotechnology e.V., Greifswald, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Markert
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Sixing
authors.initials: S
authors.lastname: Huang
authors.affiliation: UPMC University Paris 6 and CNRS, UMR 7139 Marine Plants and Biomolecules, Station Biologique de Roscoff, Roscoff, Bretagne, France.
authors.forename: Tristan
authors.initials: T
authors.lastname: Barbeyron
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Harder
authors.affiliation: Institute of Microbiology, Ernst-Moritz-Arndt-University, Greifswald, Germany.
authors.forename: Dörte
authors.initials: D
authors.lastname: Becher
authors.affiliation: 1] Institute of Marine Biotechnology e.V., Greifswald, Germany [2] Pharmaceutical Biotechnology, Ernst-Moritz-Arndt-University, Greifswald, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schweder
authors.affiliation: 1] Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany [2] Jacobs University Bremen gGmbH, Bremen, Germany.
authors.forename: Frank Oliver
authors.initials: FO
authors.lastname: Glöckner
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Rudolf I
authors.initials: RI
authors.lastname: Amann
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Hanno
authors.initials: H
authors.lastname: Teeling
mesh_terms: D002241:Carbohydrates / Q000737:chemistry; D002809:Chondroitin Sulfates / Q000737:chemistry; D017377:Diatoms / Q000254:growth & development*; D017753:Ecosystem; D005068:Eutrophication; D041965:Flavobacteriaceae / Q000235:genetics / Q000378:metabolism*; D016680:Genome, Bacterial; D023281:Genomics; D005936:Glucans / Q000737:chemistry; D008027:Light; D008353:Mannitol / Q000737:chemistry; D009659:North Sea; D010802:Phylogeny; D010839:Phytoplankton / Q000254:growth & development; D010933:Plankton / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism; D011506:Proteins / Q000737:chemistry; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D002241:Carbohydrates; D005936:Glucans; D011134:Polysaccharides; D011506:Proteins; D012336:RNA, Ribosomal, 16S; D008353:Mannitol; D002809:Chondroitin Sulfates; C008247:laminaran