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Front. Microbiol. | doi: 10.3389/fmicb.2018.01359

Comparative Metagenomics Provides Insight into the Ecosystem Functioning of the Shark Bay Stromatolites, Western Australia

  • 1Microbiology and Cell Science, University of Florida, United States
  • 2Microbiology and Cell Science, University of Florida, United States
  • 3Genomics of Gene Expression Laboratory, Centro de Investigacion Principe Felipe (CIPF), Spain
  • 4Eura nova(France), France
  • 5Rosentiel School of Marine and Atmospheric Science, University of Miami, United States

Stromatolites are organosedimentary build-ups that have formed as a result of the sediment trapping, binding and precipitating activities of microbes. Today, extant systems provide an ideal platform for understanding the structure, composition, and interactions between stromatolite-forming microbial communities and their respective environments. In this study, we compared the metagenomes of three prevalent stromatolite-forming microbial mat types in the Spaven Province of Hamelin Pool, Shark Bay located in Western Australia. These stromatolite-forming mat types included an intertidal pustular mat as well as a smooth and colloform mat types located in the subtidal zone. Additionally, the metagenomes of an adjacent, non-lithifying mat located in the upper intertidal zone were also sequenced for comparative purposes. Taxonomic and functional gene analyses revealed distinctive differences between the lithifying and non-lithifying mat types, which strongly correlated with water depth. Three distinct populations emerged including the upper intertidal non-lithifying mats, the intertidal pustular mats associated with unlaminated carbonate build-ups, and the subtidal colloform and smooth mat types associated with laminated structures. Functional analysis of metagenomes revealed that amongst stromatolite-forming mats there was an enrichment of photosynthesis pathways in the pustular stromatolite-forming mats. In the colloform and smooth stromatolite-forming mats, however, there was an increase in the abundance of genes associated with those heterotrophic metabolisms typically associated with carbonate mineralization, such as sulfate reduction. The comparative metagenomic analyses suggest that stromatolites of Hamelin Pool may form by two distinctive processes that are highly dependent on water depth. These results provide key insight into the potential adaptive strategies and synergistic interactions between microbes and their environments that may lead to stromatolite formation and accretion.

Keywords: stromatolite, microbial mat, Microbialite, Comparative metagenomics, Hamelin Pool, Shark conservation

Received: 07 Jan 2018; Accepted: 05 Jun 2018.

Edited by:

Dennis A. Bazylinski, University of Nevada, Las Vegas, United States

Reviewed by:

Virginia H. Albarracín, Center for Electron Microscopy (CIME), Argentina
BRENDAN P. BURNS, University of New South Wales, Australia  

Copyright: © 2018 Babilonia, Foster, Conesa, Casaburi, Pereira, Louyakis and Reid. 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 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. Jamie S. Foster, University of Florida, Microbiology and Cell Science, Space Life Science Lab, 505 Odyssey Way, Gainesville, 32953, FL, United States, jfoster@ufl.edu