Microbial Community Structure and Metabolic Networks in Polar Glaciers

Abstract

Polar glaciers are inhabited by numerous microorganisms including representatives of bacteria, archaea, microeukaryotes, and viruses. Low temperature is a main factor when considering polar glaciers as extreme environments. However, desiccation, low nutrients availability, ultraviolet irradiation, and photoreactive chemistry do also significantly influence their challenging life. Glaciers are highly selective and confined habitats, which make them favorable environments for adaptation and speciation. Depending on the glacier area studied, microorganisms establish a vertical food chain, from the surface photosynthesizers in upper illuminated layers to chemoautotrophs and heterotrophs confined to the inner part. These regions are rich not only in biodiversity but also in new mechanisms of adaptation to the environment, since selection acts with a particular intensity. Glaciers are retreating in many areas of the world due to global warming. When glaciers have ultimately withdrawn, microorganisms play a main role, carrying out key processes in the development of soil and facilitating plant colonization. These features make them unique and interesting for the study and protection of the biological heritage. Metagenomics have allowed a deeper understanding of microbial ecology and function of polar glacier microbial communities. In this review, we present a complete analysis of the microbial diversity in these ecosystems and include a thorough overview of the metabolic potentials and biogeochemical cycles in polar glacier habitats.

Microbial Community Structure Driven by a Volcanic Gradient in Glaciers of the Antarctic Archipelago South Shetland

“…Then, Illumina sequencing was applied to each sampling replicate. Purified DNA was quantified and 1ng of input DNA was used in a first PCR of 20 cycles with Q5 ® Hot Start High-Fidelity DNA Polymerase (New England Biolabs) in the presence of 100nM primers of the regions V3 and V4 of the 16S rRNA gene, or of the region V4 and V5 region of the 18S rRNA gene as previously reported [ 21 , 22 ]. Primers sequences were: V3-V4 (Forward ACACTGACGACATGG TTCTACACCTACGGGNGGCWGCAG, Reverse TACGGTACGACTTGGTCTGTACHV GGGTATCTAATCC); V4-V5 (Forward GCCCAVCYGCGGTAAY, Reverse CCGTCAATTHCTTYAART).…”

Glacier clear ice bands indicate englacial channel microbial distribution

“…Widespread understanding of glaciers as biomes has only been achieved in the past few decades (Anesio and Laybourn-Parry, 2012). Glacial biomes are microbially dominated and are usually divided into three different environments: the glacial surface (supraglacial), within its interior (englacial) and at the base where the glacier is in contact with the bedrock (subglacial) (Anesio and others, 2017; García-López and others, 2019a). Supraglacial studies have mainly been focused on cryoconite holes (Fountain and others, 2004; Tranter and others, 2004; Bagshaw and others, 2007; Edwards and others, 2011; Musilova and others, 2015; Cook and others, 2016; Uetake and others, 2019) and ice algae-associated communities (Uetake and others, 2010; Yallop and others, 2012; Lutz and others, 2017), both of which are dominated by phototrophs.…”