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Genomic diversity and CRISPR-Cas systems in the cyanobacterium Nostoc in the High Arctic.

https://arctichealth.org/en/permalink/ahliterature311096
Source
Environ Microbiol. 2021 Mar 24; :
Publication Type
Journal Article
Date
Mar-24-2021
Author
Anne D Jungblut
Frédéric Raymond
Moïra B Dion
Sylvain Moineau
Vani Mohit
Guillaume Q H Nguyen
Maxime Deraspe
Elina Francovic-Fontaine
Connie Lovejoy
Alexander I Culley
Jacques Corbeil
Warwick F Vincent
Author Affiliation
Life Sciences Department, Natural History Museum, Cromwell Road, SW7 5BD, London, United Kingdom.
Source
Environ Microbiol. 2021 Mar 24; :
Date
Mar-24-2021
Language
English
Publication Type
Journal Article
Abstract
Nostoc (Nostocales, Cyanobacteria) has a global distribution in the Polar Regions. However, the genomic diversity of Nostoc is little known and there are no genomes available for polar Nostoc. Here we carried out the first genomic analysis of the N. commune morphotype with a recent sample from the High Arctic and a herbarium specimen collected during the British Arctic Expedition (1875-76). Comparisons of the polar genomes with 26 present-day non-polar members of the Nostocales family highlighted that there are pronounced genetic variations among Nostoc strains and species. Osmoprotection and other stress genes were found in all Nostoc strains, but the two Arctic strains had markedly higher numbers of biosynthetic gene clusters for uncharacterised nonribosomal peptide synthetases, suggesting a high diversity of secondary metabolites. Since viral-host interactions contribute to microbial diversity, we analysed the CRISPR-Cas systems in the Arctic and two temperate Nostoc species. There were a large number of unique repeat-spacer arrays in each genome, indicating diverse histories of viral attack. All Nostoc strains had a subtype I-D system, but the polar specimens also showed evidence of a subtype I-B system that has not been previously reported in cyanobacteria, suggesting diverse cyanobacteria-virus interactions in the Arctic. This article is protected by copyright. All rights reserved.
PubMed ID
33760341 View in PubMed
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Hidden biofilms in a far northern lake and implications for the changing Arctic.

https://arctichealth.org/en/permalink/ahliterature283908
Source
NPJ Biofilms Microbiomes. 2017;3:17
Publication Type
Article
Date
2017
Author
Vani Mohit
Alexander Culley
Connie Lovejoy
Frédéric Bouchard
Warwick F Vincent
Source
NPJ Biofilms Microbiomes. 2017;3:17
Date
2017
Language
English
Publication Type
Article
Abstract
Shallow lakes are common across the Arctic landscape and their ecosystem productivity is often dominated by benthic, cyanobacterial biofilms. Many of these water bodies freeze to the bottom and are biologically inactive during winter, but full freeze-up is becoming less common with Arctic warming. Here we analyzed the microbiome structure of newly discovered biofilms at the deepest site of a perennially ice-covered High Arctic lake as a model of polar microbial communities that remain unfrozen throughout the year. Biofilms were also sampled from the lake's shallow moat region that melts out and refreezes to the bottom annually. Using high throughput small subunit ribosomal RNA sequencing, we found more taxonomic richness in Bacteria, Archaea and microbial eukaryotes in the perennially unfrozen biofilms compared to moat communities. The deep communities contained both aerobic and anaerobic taxa including denitrifiers, sulfate reducers, and methanogenic Archaea. The water overlying the deep biofilms was well oxygenated in mid-summer but almost devoid of oxygen in spring, indicating anoxia during winter. Seasonally alternating oxic-anoxic regimes may become increasingly widespread in polar biofilms as fewer lakes and ponds freeze to the bottom, favoring prolonged anaerobic metabolism and greenhouse gas production during winter darkness.
PubMed ID
28702216 View in PubMed
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Multiple Strategies for Light-Harvesting, Photoprotection, and Carbon Flow in High Latitude Microbial Mats.

https://arctichealth.org/en/permalink/ahliterature296774
Source
Front Microbiol. 2018; 9:2881
Publication Type
Journal Article
Date
2018
Author
Adrien Vigneron
Perrine Cruaud
Vani Mohit
Marie-Josée Martineau
Alexander I Culley
Connie Lovejoy
Warwick F Vincent
Author Affiliation
Centre d'Études Nordiques, Takuvik Joint International Laboratory, Université Laval, Québec, QC, Canada.
Source
Front Microbiol. 2018; 9:2881
Date
2018
Language
English
Publication Type
Journal Article
Abstract
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.
PubMed ID
30564204 View in PubMed
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