Ecology of Subglacial Lake Vostok (Antarctica), Based on Metagenomic/Metatranscriptomic Analyses of Accretion Ice

Abstract

Lake Vostok is the largest of the nearly 400 subglacial Antarctic lakes and has been continuously buried by glacial ice for 15 million years. Extreme cold, heat (from possible hydrothermal activity), pressure (from the overriding glacier) and dissolved oxygen (delivered by melting meteoric ice), in addition to limited nutrients and complete darkness, combine to produce one of the most extreme environments on Earth. Metagenomic/metatranscriptomic analyses of ice that accreted over a shallow embayment and over the southern main lake basin indicate the presence of thousands of species of organisms (94% Bacteria, 6% Eukarya, and two Archaea). The predominant bacterial sequences were closest to those from species of Firmicutes, Proteobacteria and Actinobacteria, while the predominant eukaryotic sequences were most similar to those from species of ascomycetous and basidiomycetous Fungi. Based on the sequence data, the lake appears to contain a mixture of autotrophs and heterotrophs capable of performing nitrogen fixation, nitrogen cycling, carbon fixation and nutrient recycling. Sequences closest to those of psychrophiles and thermophiles indicate a cold lake with possible hydrothermal activity. Sequences most similar to those from marine and aquatic species suggest the presence of marine and freshwater regions.

Microbial ecology of Antarctic aquatic systems

“…Exploration leading to penetration into Lake Vostok, the largest of the subglacial lakes, which sits below ~3.8 km of ice, has suffered a very challenging history 1,[114][115][116] . Unfortunately, this raises questions about the veracity of the interpretation of data for indigenous lake microorganisms, including data gathered using metagenomics and metatranscriptomics 117,118 . To avoid the problems associated with using drilling fluid and 60,000 litres of kerosene to keep the bore hole open at Vostok 113 , an attempt was made to use hot water to penetrate ~3.4 km into Lake Ellsworth, but the effort failed at ~300 m, and the project was abandoned 116,119 .…”

Evidence of plant and animal communities at exposed and subglacial (cave) geothermal sites in Antarctica

“…Despite recent advances in our broad understanding of Antarctic biodiversity (Chown et al 2015), we still know little about life in the continent's subglacial cave systems, which may harbour diverse and complex communities. Emerging molecular evidence for life in subglacial Lake Vostok, more than 3700 m below the surface of the East Antarctic Ice Sheet (Rogers et al 2013;Shtarkman et al 2013), and Lake Whillans, 800 m beneath the West Antarctic Ice Sheet (Christner et al 2014), has helped us to begin to understand the broad importance of subglacial ecosystems for polar biodiversity.…”

Preliminary Analysis of Life within a Former Subglacial Lake Sediment in Antarctica

“…More recently, Rogers et al [22] have published data from a metagenomic/metatranscriptomic analysis of Lake Vostok accretion ice. They found sequences that indicated the presence of thousands of species of microorganisms (94% Bacteria, 6% Eukarya, and two Archaea).…”