title: 'Candidatus Ancillula trichonymphae', a novel lineage of endosymbiotic Actinobacteria in termite gut flagellates of the genus Trichonympha.
abstract: Termite gut flagellates are colonized by host-specific lineages of ectosymbiotic and endosymbiotic bacteria. Previous studies have shown that flagellates of the genus Trichonympha may harbour more than one type of symbiont. Using a comprehensive approach that combined cloning of SSU rRNA genes with fluorescence in situ hybridization and electron microscopy, we investigated the phylogeny and subcellular locations of the symbionts in a variety of Trichonympha species from different termites. The flagellates in Trichonympha Cluster I were the only species associated with 'Endomicrobia', which were located in the posterior part of the cell, confirming previous results. Trichonympha species of Cluster II from the termite genus Incisitermes (family Kalotermitidae) lacked 'Endomicrobia' and were associated with endosymbiotic Actinobacteria, which is highly unusual. The endosymbionts, for which we suggest the name 'Candidatus Ancillula trichonymphae', represent a novel, deep-branching lineage in the Micrococcineae that consists exclusively of clones from termite guts. They preferentially colonized the anterior part of the flagellate host and were highly abundant in all species of Trichonympha Cluster II except Trichonympha globulosa. Here, they were outnumbered by a Desulfovibrio species associated with the cytoplasmic lamellae at the anterior cell pole. Such symbionts are present in both Trichonympha clusters, but not in all species. Unlike the intracellular location reported for the Desulfovibrio symbionts of Trichonympha agilis (Cluster I), the Desulfovibrio symbionts of T. globulosa (Cluster II) were situated in deep invaginations of the plasma membrane that were clearly connected to the exterior of the host cell.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Department of Biogeochemistry, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany.
authors.forename: Jürgen F H
authors.initials: JF
authors.lastname: Strassert
authors.forename: Tim
authors.initials: T
authors.lastname: Köhler
authors.forename: Tobias H G
authors.initials: TH
authors.lastname: Wienemann
authors.forename: Wakako
authors.initials: W
authors.lastname: Ikeda-Ohtsubo
authors.forename: Nicolas
authors.initials: N
authors.lastname: Faivre
authors.forename: Sibylle
authors.initials: S
authors.lastname: Franckenberg
authors.forename: Rudy
authors.initials: R
authors.lastname: Plarre
authors.forename: Renate
authors.initials: R
authors.lastname: Radek
authors.forename: Andreas
authors.initials: A
authors.lastname: Brune
mesh_terms: D039903:Actinobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D000818:Animals; D003001:Cloning, Molecular; D003901:Desulfovibrio / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D041981:Gastrointestinal Tract / Q000382:microbiology*; D020459:Genes, rRNA; D056952:Hypermastigia / Q000145:classification* / Q000302:isolation & purification / Q000502:physiology / Q000648:ultrastructure; D020049:Isoptera / Q000382:microbiology*; D010802:Phylogeny; D013045:Species Specificity; D013559:Symbiosis / Q000235:genetics