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Title: Candidatus Adiutrix intracellularis’, an endosymbiont of termite gut flagellates, is the first representative of a deep-branching clade of Deltaproteobacteria and a putative homoacetogen

Termite gut flagellates are typically colonized by specific bacterial symbionts. Here we describe the phylogeny, ultrastructure and subcellular location of 'Candidatus Adiutrix intracellularis', an intracellular symbiont of Trichonympha collaris in the termite Zootermopsis nevadensis. It represents a novel, deep-branching clade of uncultured Deltaproteobacteria widely distributed in intestinal tracts of termites and cockroaches. Fluorescence in situ hybridization and transmission electron microscopy localized the endosymbiont near hydrogenosomes in the posterior part and near the ectosymbiont 'Candidatus Desulfovibrio trichonymphae' in the anterior part of the host cell. The draft genome of 'Ca. Adiutrix intracellularis' obtained from a metagenomic library revealed the presence of a complete gene set encoding the Wood-Ljungdahl pathway, including two homologs of fdhF encoding hydrogenase-linked formate dehydrogenases (FDHH ) and all other components of the recently described hydrogen-dependent carbon dioxide reductase (HDCR) complex, which substantiates previous claims that the symbiont is capable of reductive acetogenesis from CO2 and H2 . The close phylogenetic relationship between the HDCR components and their homologs in homoacetogenic Firmicutes and Spirochaetes suggests that the deltaproteobacterium acquired the capacity for homoacetogenesis via lateral gene transfer. The presence of genes for nitrogen fixation and the biosynthesis of amino acids and cofactors indicate the nutritional nature of themore » symbiosis.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ; ORCiD logo [1]
  1. Max Planck Inst. for Terrestrial Microbiology, Marburg (Germany). Dept. of Biogeochemistry
  2. Max Planck Inst. for Terrestrial Microbiology, Marburg (Germany). Dept. of Biogeochemistry; Free Univ. of Berlin, Berlin (Germany). Inst. of Biology/Zoology
  3. Helmholtz Center for Infection Research, Braunschweig (Germany). Computational Biology of Infection Research; Heinrich Heine Univ. Dusseldorf, Dusseldorf (Germany). Dept. of Algorithmic Bioinformatics
  4. USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States)
  5. USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Univ. of Queensland, Brisbane (Australia). Australian Centre for Ecogenomics
  6. Free Univ. of Berlin, Berlin (Germany). Inst. of Biology/Zoology
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Environmental Microbiology
Additional Journal Information:
Journal Volume: 18; Journal Issue: 8; Journal ID: ISSN 1462-2912
Publisher:
Wiley
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; termite gut flagellates, intracellular symbionts; reductive acetogenesis; hydrogen; Deltaproteobacteria
OSTI Identifier:
1409424