Eukaryotic microorganisms in cold environments: examples from Pyrenean glaciers

Abstract

Little is known about the viability of eukaryotic microorganisms preserved in icy regions. Here we report on the diversity of microbial eukaryotes in ice samples derived from four Pyrenean glaciers. The species composition of eukaryotic communities in these glaciers is unknown mostly because of the presence of a multi-year ice cap, and it is not clear whether they harbor the same populations. The recent deglaciation of these areas is allowing an easy access to glacial layers that correspond to the “Little Ice Age” although some isolated deposits are attributed to previous glacial cycles. In this study, we use molecular 18S rRNA-based approaches to characterize some of the microbial eukaryotic populations associated with Pyrenean glaciers. Firstly, we performed a chemical and microscopical characterization of ice samples. Secondly, molecular analyses revealed interesting protist genetic diversity in glaciers. In order to understand the microbial composition of the ice samples the eukaryotic communities resident in the glacial samples were examined by amplifying community DNA and constructing clone libraries with 18S rRNA primers. After removal of potential chimeric sequences and dereplication of identical sequences, phylogenetic analysis demonstrated that several different protists could be identified. Protist diversity was more phylum rich in Aneto and Monte Perdido glaciers. The dominant taxonomic groups across all samples (>1% of all sequences) were Viridiplantae and Rhizaria. Significant variations in relative abundances of protist phyla between higher and lower glaciers were observed. At the genus level, significant differences were also recorded for the dominant genera Chloromonas, Raphidonema, Heteromita, Koliella, and Bodomorpha. In addition, protist community structure showed significant differences between glaciers. The relative abundances of protist groups at different taxonomic levels correlated with the altitude and area of glaciers and with pH of ice, but little or no relationships to other chemical characteristics were found.

Microbial Communities in Coastal Glaciers and Tidewater Tongues of Svalbard Archipelago, Norway

“…Microbial communities associated with glaciers found all over the world, are being increasingly studied. Specifically, these microorganisms have been reported in Polar Arctic (Amato et al, 2007;Hell et al, 2013;Larose et al, 2013) and Antarctic Regions (Foreman et al, 2007) and in high mountains (Garcia-Descalzo et al, 2013;Hotaling et al, 2017). However, glaciers are very different from each other, which influence the life of their inhabitants.…”

“…It is essential to know how climate change is shaping the distribution and diversity of microbial communities, as microorganisms participate particularly in the ecology of the Arctic ecosystems. They constitute the basis of trophic networks and they are an essential element in carbon and nutrient cycling (Hoham and Duval, 2001;Garcia-Descalzo et al, 2013).…”

Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion

“…21–24 Whereas numerous aerobic methanotrophs have been cultured in the laboratory and there is relatively little controversy over the enzymes and the metabolic intermediates involved in aerobic methane oxidation, 1,2,9,10,25 the inability to obtain pure cultures of ANME has complicated the elucidation of its biochemistry, leaving many aspects of AOM still contested. 24,26–30 Ultimately, we must determine whether the methane oxidation enzymes involved in these processes possess commercial potential or are simply toys to be played with in the laboratory.…”

Microbial Community Structure and Metabolic Networks in Polar Glaciers

“…Between 1975 and 2005, most of the DNA sequences were obtained through the application of the Sanger techniques [34], which led to the first generation of automated DNA sequencers [35] (Figure 4). For 16S or 18S rRNA sequencing, PCR amplification was carried out with specific primers ( Table 1) and sequencing instruments based on capillary electrophoresis.…”