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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Microbiol. | doi: 10.3389/fmicb.2019.01658

Evolutionary Implications of Anoxygenic Phototrophy in the Bacterial Phylum Candidatus Eremiobacterota (WPS-2)

  • 1Harvard University, United States
  • 2Imperial College London, United Kingdom
  • 3University of Colorado Boulder, United States

Genome-resolved environmental metagenomic sequencing has uncovered substantial previously unrecognized microbial diversity relevant for understanding the ecology and evolution of the biosphere, providing a more nuanced view of the distribution and ecological significance of traits including phototrophy across diverse niches. Recently, the capacity for bacteriochlorophyll-based anoxygenic photosynthesis has been found in the uncultured bacterial WPS-2 phylum (recently proposed as Candidatus Eremiobacterota) that are in close association with boreal moss. Here, we use phylogenomic analysis to investigate the diversity and evolution of phototrophic WPS-2. We demonstrate that phototrophic WPS-2 show significant genetic and metabolic divergence from other phototrophic and non-phototrophic lineages. The genomes of these organisms encode a completely new family of anoxygenic Type II photochemical reaction centers and other phototrophy-related proteins that are both phylogenetically and structurally distinct from those found in previously described phototrophs. We propose the name Candidatus Baltobacterales for the order-level aerobic WPS-2 clade which contains phototrophic lineages, from the Greek for “bog” or “swamp”, in reference to the typical habitat of phototrophic members of this clade.

Keywords: Phototrophy, WPS-2, anoxygenic, Chloroflexi, reaction center

Received: 11 Mar 2019; Accepted: 04 Jul 2019.

Edited by:

Iain Sutcliffe, Northumbria University, United Kingdom

Reviewed by:

Yonghui Zeng, Aarhus University, Denmark
Donald A. Bryant, Pennsylvania State University, United States  

Copyright: © 2019 Ward, Cardona and Holland-Moritz. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Lewis M. Ward, Harvard University, Cambridge, MA 02138, Massachusetts, United States, lewis_ward@fas.harvard.edu
Dr. Tanai Cardona, Imperial College London, London, United Kingdom, t.cardona@imperial.ac.uk
Ms. Hannah Holland-Moritz, University of Colorado Boulder, Boulder, 80309, Colorado, United States, hannah.hollandmoritz@colorado.edu