From strains to communities : an omics approach to study the diversity and adaptation of Antarctic cyanobacteria

• Main Author: Savaglia, Valentina
• Other Authors: Wilmotte, Annick, Verleyen, Elie
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Ghent University. Faculty of Sciences 2023
• Subjects: Biology and Life Sciences; Antarctic; The Antarctic; East Antarctica; Sør-Rondane; Sør Rondane Mountains; Antarc*; Antarctica
• Online Access: https://biblio.ugent.be/publication/01HCHJ34R9PQQSWY1RT307YYVN; http://hdl.handle.net/1854/LU-01HCHJ34R9PQQSWY1RT307YYVN; https://biblio.ugent.be/publication/01HCHJ34R9PQQSWY1RT307YYVN/file/01HCHJ786QZGY6AB4R2TX9RX44

Ice-free areas cover less than 0.5 % of the Antarctic, yet they host most of the terrestrial biodiversity of the whole continent. These terrestrial habitats are characterized by truncated and simple food webs consisting almost uniquely of microbial communities. Cyanobacteria are among the main primary producers in these habitats where they are often regarded as ‘ecosystem engineers. Despite the important ecological role cyanobacteria play, our understanding of the factors shaping their diversity and community structure, as well as their adaptions to cope with the extreme abiotic conditions in the Antarctic remains limited. The main aims of this Ph.D. were to (1) characterize the community structure and distribution of bacteria and micro-eukaryotes in a variety of substrates from different nunataks and valleys of the Sør Rondane Mountains region (East Antarctica); (2) identify keystone taxa in these food-webs and the main abiotic factors structuring these communities (Chapter 2); (3) provide a detailed understanding of the cyanobacterial diversity and community structure in these regions (Chapter 3); (4) identify the main physiological and genetic adaptation mechanisms that a pair of species of Nostoc (cyanobacteria) employ under desiccation – rehydration events which frequently occur the terrestrial environments of the Antarctic (Chapter 4). To achieve these goals, a multidisciplinary approach was applied combining ecophysiological and several omics analyses. In Chapter 2, the composition of bacterial and micro-eukaryotic communities was examined using high-throughput sequencing of parts of the 16S rRNA and 18S rRNA genes in 105 soil samples across 9 sites within a 100 km radius in the Sør Rondane Mountains (East Antarctica), differing in substrate type and associated physical and chemical conditions. In moraine soils, Actinomycetota and Cercozoa were among the most abundant bacterial and eukaryotic phyla, whereas on gneiss, granite and marble bedrock, Cyanobacteriota and Metazoa were the among the dominant ...