title: Census of bacterial microbiota associated with the glacier ice worm Mesenchytraeus solifugus.
abstract: The glacier ice worm, Mesenchytraeus solifugus, is a unique annelid, inhabiting only snow and ice in North American glaciers. Here, we analyzed the taxonomic composition of bacteria associated with M. solifugus based on the 16S rRNA gene. We analyzed four fixed-on-site and 10 starved ice worm individuals, along with glacier surface samples. In total, 1341 clones of 16S rRNA genes were analyzed for the ice worm samples, from which 65 bacterial phylotypes (99.0% cut-off) were identified. Of these, 35 phylotypes were closely related to sequences obtained from their habitat glacier and/or other components of cryosphere; whereas three dominant phylotypes were affiliated with animal-associated lineages of the class Mollicutes. Among the three, phylotype Ms-13 shared less than 89% similarity with database sequences and was closest to a gut symbiont of a terrestrial earthworm. Using fluorescence in situ hybridization, Ms-13 was located on the gut wall surface of the ice worms. We propose a novel genus and species, 'Candidatus Vermiplasma glacialis', for this bacterium. Our results raise the possibility that the ice worm has exploited indigenous glacier bacteria, while several symbiotic bacterial lineages have maintained their association with the ice worm during the course of adaptive evolution to the permanently cold environment.
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, Tokyo 152-8550, Japan tmurakami@bio.titech.ac.jp.
authors.forename: Takumi
authors.initials: T
authors.lastname: Murakami
authors.affiliation: National Institute of Polar Research, Tokyo 190-8518, Japan Transdisciplinary Research Integration Center, Tokyo 190-8518, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Segawa
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, Tokyo 152-8550, Japan.
authors.forename: Dylan
authors.initials: D
authors.lastname: Bodington
authors.affiliation: Department of Environmental Science, Alaska Pacific University, Alaska 99508, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Dial
authors.affiliation: Department of Earth Sciences, Chiba University, Chiba 263-8522, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Takeuchi
authors.affiliation: Wildlife Research Center, Kyoto University, Kyoto 606-8203, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Kohshima
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, Tokyo 152-8550, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hongoh
mesh_terms: D000818:Animals; D000845:Annelida / Q000382:microbiology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D041981:Gastrointestinal Tract / Q000382:microbiology*; D046448:Ice Cover / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D064307:Microbiota / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D008973:Tenericutes / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: 16S rRNA; enchytraeid; glacier ecology; gut bacteria; symbiosis