title: "Candidatus Thiobios zoothamnicoli," an ectosymbiotic bacterium covering the giant marine ciliate Zoothamnium niveum.
abstract: Zoothamnium niveum is a giant, colonial marine ciliate from sulfide-rich habitats obligatorily covered with chemoautotrophic, sulfide-oxidizing bacteria which appear as coccoid rods and rods with a series of intermediate shapes. Comparative 16S rRNA gene sequence analysis and fluorescence in situ hybridization showed that the ectosymbiont of Z. niveum belongs to only one pleomorphic phylotype. The Z. niveum ectosymbiont is only moderately related to previously identified groups of thiotrophic symbionts within the Gammaproteobacteria, and shows highest 16S rRNA sequence similarity with the free-living sulfur-oxidizing bacterial strain ODIII6 from shallow-water hydrothermal vents of the Mediterranean Sea (94.5%) and an endosymbiont from a deep-sea hydrothermal vent gastropod of the Indian Ocean Ridge (93.1%). A replacement of this specific ectosymbiont by a variety of other bacteria was observed only for senescent basal parts of the host colonies. The taxonomic status "Candidatus Thiobios zoothamnicoli" is proposed for the ectosymbiont of Z. niveum based on its ultrastructure, its 16S rRNA gene, the intergenic spacer region, and its partial 23S rRNA gene sequence.
authors.affiliation: Department of Marine Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria. rinke@gmx.at
authors.forename: Christian
authors.initials: C
authors.lastname: Rinke
authors.forename: Stephan
authors.initials: S
authors.lastname: Schmitz-Esser
authors.forename: Kilian
authors.initials: K
authors.lastname: Stoecker
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Nussbaumer
authors.forename: Dávid A
authors.initials: DA
authors.lastname: Molnár
authors.forename: Katrina
authors.initials: K
authors.lastname: Vanura
authors.forename: Michael
authors.initials: M
authors.lastname: Wagner
authors.forename: Matthias
authors.initials: M
authors.lastname: Horn
authors.forename: Jörg A
authors.initials: JA
authors.lastname: Ott
authors.forename: Monika
authors.initials: M
authors.lastname: Bright
mesh_terms: D000818:Animals; D016798:Ciliophora / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D020563:Gammaproteobacteria / Q000145:classification* / Q000235:genetics / Q000648:ultrastructure; D020459:Genes, rRNA; D017404:In Situ Hybridization, Fluorescence; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012623:Seawater / Q000469:parasitology*; D017422:Sequence Analysis, DNA; D013440:Sulfides / Q000378:metabolism; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S; D013440:Sulfides