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Title: Refining the phylum Chlorobi by resolving the phylogeny and metabolic potential of the representative of a deeply branching, uncultivated lineage

Recent studies have expanded the phylum Chlorobi, demonstrating that the green sulfur bacteria (GSB), the original cultured representatives of the phylum, are a part of a larger lineage whose members have more diverse metabolic capabilities that overlap with members of the phylum Bacteroidetes. The 16S rRNA gene of an uncultivated clone, OPB56, distantly related to the phyla Chlorobi and Bacteroidetes, was recovered from Obsidian Pool in Yellowstone National Park; however, the detailed phylogeny and function of OPB56 and related clones have remained unknown. Culturing of thermophilic bacterial consortia from compost by adaptation to grow on ionic-liquid pretreated switchgrass provided a consortium in which one of the most abundant members, NICIL-2, clustered with OPB56-related clones. Phylogenetic analysis using the full-length 16S rRNA gene from NICIL-2 demonstrated that it was part of a monophyletic clade, referred to as OPB56, distinct from the Bacteroidetes and Chlorobi. A near complete draft genome ( > 95% complete) was recovered from metagenomic data from the culture adapted to grow on ionic-liquid pretreated switchgrass using an automated binning algorithm, and this genome was used for marker gene-based phylogenetic analysis and metabolic reconstruction. Six additional genomes related to NICIL-2 were reconstructed from metagenomic data sets obtained from thermalmore » springs at Yellowstone National Park and Nevada Great Boiling Spring. In contrast to the 16S rRNA gene phylogenetic analysis, protein phylogenetic analysis was most consistent with the clustering of the Chlorobea, Ignavibacteria and OPB56 into a single phylum level clade. Metabolic reconstruction of NICIL-2 demonstrated a close linkage with the class Ignavibacteria and the family Rhodothermaceae, a deeply branching Bacteroidetes lineage. The combined phylogenetic and functional analysis of the NICIL-2 genome has refined the membership in the phylum Chlorobi and emphasized the close evolutionary and metabolic relationship between the phyla Chlorobi and the Bacteroidetes.« less
 [1] ;  [1] ;  [2] ;  [3] ;  [1]
  1. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of Vienna (Austria)
  3. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
The ISME Journal
Additional Journal Information:
Journal Volume: 10; Journal Issue: 4; Journal ID: ISSN 1751-7362
Nature Publishing Group
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
OSTI Identifier: