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

Front. Microbiol. | doi: 10.3389/fmicb.2019.01983

Ecology of Subseafloor Crustal Biofilms

 Gustavo A. Ramírez1, Arkadiy Garber2, Aurélien Lecoeuvre3,  Tim D'Angelo4,  Charles G. Wheat5 and  Beth N. Orcutt4*
  • 1University of Rhode Island, United States
  • 2University of Montana, United States
  • 3Université de Bretagne Occidentale, France
  • 4Bigelow Laboratory For Ocean Sciences, United States
  • 5University of Alaska Fairbanks, United States

The crustal subseafloor is the least explored and largest biome on Earth. Interrogating crustal life is difficult due to habitat inaccessibility, low-biomass and contamination challenges. Subseafloor observatories have facilitated the study of planktonic life in crustal aquifers, however, studies of life in crust-attached biofilms are rare. Here, we investigate biofilms grown on various minerals at different temperatures over 1-6 years at subseafloor observatories in the Eastern Pacific. To mitigate potential sequence contamination, we developed a new bioinformatics tool –TaxonSluice. We explore ecological factors driving community structure and potential function of biofilms by comparing our sequence data to previous amplicon and metagenomic surveys of this habitat. We reveal that biofilm community structure is driven by temperature rather than minerology, and that rare planktonic lineages colonize the crustal biofilms. Based on 16S rRNA gene overlap, we partition metagenome assembled genomes into planktonic and biofilm fractions and suggest that there are functional differences between these community types, emphasizing the need to separately examine each to accurately describe subseafloor microbe-rock-fluid processes. Lastly, we report that some rare lineages present in our warm and anoxic study site are also found in cold and oxic crustal fluids in the Mid-Atlantic Ridge, suggesting global crustal biogeography patterns.

Keywords: deep biosphere, subseafloor, oceanic crust, Juan de Fuca eastern flank, CORK, Flocs, low biomass

Received: 02 May 2019; Accepted: 13 Aug 2019.

Edited by:

Sabin Zahirovic, University of Sydney, Australia

Reviewed by:

Ruiyong Zhang, Federal Institute For Geosciences and Natural Resources, Germany
James F. Holden, University of Massachusetts Amherst, United States
Craig L. Moyer, Western Washington University, United States  

Copyright: © 2019 Ramírez, Garber, Lecoeuvre, D'Angelo, Wheat and Orcutt. 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. Beth N. Orcutt, Bigelow Laboratory For Ocean Sciences, Boothbay, Maine, United States, borcutt@bigelow.org