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Front. Microbiol. | doi: 10.3389/fmicb.2018.02881

Multiple Strategies for Light-Harvesting, Photoprotection and Carbon Flow in High Latitude Microbial Mats

  • 1Laval University, Canada

Microbial mats are ubiquitous in polar freshwater ecosystems and sustain high concentrations of biomass despite the extreme seasonal variations in light and temperature. Here we aimed to resolve genomic adaptations for light-harvesting, bright-light protection and carbon flow in mats that undergo seasonal freeze-up. To bracket a range of communities in shallow water habitats, we sampled cyanobacterial mats in the thawed littoral zone of two lakes situated at the northern and southern limits of the Canadian Arctic permafrost zone. We applied a multiphasic approach using pigment profiles from high performance liquid chromatography, Illumina MiSeq sequencing of the 16S and 18S rRNA genes, and metagenomic analysis. The mats shared a taxonomic and functional core microbiome, dominated by oxygenic cyanobacteria with light-harvesting and photoprotective pigments, bacteria with bacteriochlorophyll, and bacteria with light-driven Type I rhodopsins. Organisms able to use light for energy related processes represented up to 85% of the total microbial community, with 15-30% attributable to cyanobacteria and 55-70% attributable to other bacteria. The proportion of genes involved in anaplerotic CO2 fixation was greater than for genes associated with oxygenic photosynthesis. Diverse heterotrophic bacteria, eukaryotes (including metazoans and fungi) and viruses co-occurred in both communities. The results indicate a broad range of strategies for capturing sunlight and CO2, and for the subsequent flow of energy and carbon in these complex, light-driven microbial ecosystems.

Keywords: Arctic, microbiome, Cyanobacteria, Rhodopsin, pigment, Biofilm

Received: 15 Aug 2018; Accepted: 09 Nov 2018.

Edited by:

Samuel Cirés, Universidad Autónoma de Madrid, Spain

Reviewed by:

Purificacion Lopez-Garcia, Centre national de la recherche scientifique (CNRS), France
Anna Vader, University Centre in Svalbard, Norway  

Copyright: © 2018 Vigneron, Cruaud, Mohit, Martineau, Culley, Lovejoy and Vincent. 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: Prof. Warwick F. Vincent, Laval University, Quebec, G1V 0A6, Quebec, Canada,