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Faculté des Sciences
Faculté des Sciences
MASTER THESIS
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Microbial diversity and activity in the active layer of thawing permafrost: a case study in Northern Norway

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Quabron, Gilles ULiège
Promotor(s) : Joaquim-Justo, Célia ULiège ; Lee, Hanna
Date of defense : 3-Sep-2018 • Permalink : http://hdl.handle.net/2268.2/6023
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Title : Microbial diversity and activity in the active layer of thawing permafrost: a case study in Northern Norway
Author : Quabron, Gilles ULiège
Date of defense  : 3-Sep-2018
Advisor(s) : Joaquim-Justo, Célia ULiège
Lee, Hanna 
Committee's member(s) : Romain, Anne-Claude ULiège
Falzone, Claudia ULiège
Language : English
Number of pages : 76
Keywords : [en] permafrost thaw
[en] microbial diversity
[en] microbial activity
[en] palsa
[en] 16s rRNA
[en] qPCR
[en] mcrA
[en] pmoA
[en] Biolog
[en] beta-glucosidase
[en] climate change
[en] Norway
Discipline(s) : Life sciences > Microbiology
Research unit : Uni Research Climate
Target public : Researchers
Student
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master en sciences et gestion de l'environnement, à finalité spécialisée en surveillance de l'environnement
Faculty: Master thesis of the Faculté des Sciences

Abstract

[en] Permafrost environments, which store large quantities of soil organic carbon, are threatened by climate change-induced thaw that would render frozen organic matter bioavailable for microorganisms leading to an increase in greenhouse gases emissions. Hence understanding the response of permafrost microbial communities to thawing is necessary to evaluate the permafrost carbon feedback to global change. Microbial diversity and activity were studied across two thaw stages (intact and degrading permafrost) at different depths in a palsa found in Northern Norway. This study investigated soil microbial community composition by Illumina Miseq sequencing of the 16S rRNA gene while bacterial, archaeal, methanogens and methanotrophs abundance was assessed by qPCR. Microbial heterotrophic activity was evaluated using enzymatic and functional metabolic assays. Microbial communities’ composition and activity were found to differ between the two thaw stages. The intact palsa (IP) presented high richness that decreased with depth while the degrading palsa (DP) exhibited less species-rich communities across depth. Relative abundance of members of the phylum Proteobacteria known to thrive in higher carbon and nutrient availability increased in the DP while members of the phylum AD3, which dominated the deepest part of the IP, almost disappeared in the DP. Bacterial, archaeal, methanogens and methanotrophs were more abundant in the thawing permafrost than in the intact palsa. The DP exhibited high and similar microbial biomass across depths while the IP showed high microbial abundance only in the topsoil layer. In addition, populations of methane-producing microorganisms were found to be strongly positively correlated to methane oxidizers abundance, suggesting a close spatial relationship between these two communities. Heterotrophic prokaryotes found in the DP displayed higher enzymatic and functional metabolic activity across depth than in the IP. Collectively, these results suggest a shift in microbial prokaryotic communities as a result of permafrost thaw characterized by less species-rich populations, by an increasing biomass of greenhouse gases-related microorganisms as well as a higher microbial activity across depth, potentially leading to greater greenhouse gases emissions that would exacerbate the positive feedbacks from permafrost carbon to climate.


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Author

  • Quabron, Gilles ULiège Université de Liège > Master sc. & gest. env., à fin.

Promotor(s)

Committee's member(s)

  • Romain, Anne-Claude ULiège Université de Liège - ULiège > DER Sc. et gest. de l'environnement (Arlon Campus Environ.) > Surveillance de l'environnement
    ORBi View his publications on ORBi
  • Falzone, Claudia ULiège Université de Liège - ULiège > DER Sc. et gest. de l'environnement (Arlon Campus Environ.) > Surveillance de l'environnement
    ORBi View his publications on ORBi
  • Total number of views 120
  • Total number of downloads 380










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