Subglacial Lake Vostok (Antarctica) Accretion Ice Contains a Diverse Set of Sequences from Aquatic, Marine and Sediment-Inhabiting Bacteria and Eukarya

Abstract

Lake Vostok, the 7th largest (by volume) and 4th deepest lake on Earth, is covered by more than 3,700 m of ice, making it the largest subglacial lake known. The combination of cold, heat (from possible hydrothermal activity), pressure (from the overriding glacier), limited nutrients and complete darkness presents extreme challenges to life. Here, we report metagenomic/metatranscriptomic sequence analyses from four accretion ice sections from the Vostok 5G ice core. Two sections accreted in the vicinity of an embayment on the southwestern end of the lake, and the other two represented part of the southern main basin. We obtained 3,507 unique gene sequences from concentrates of 500 ml of 0.22 µm-filtered accretion ice meltwater. Taxonomic classifications (to genus and/or species) were possible for 1,623 of the sequences. Species determinations in combination with mRNA gene sequence results allowed deduction of the metabolic pathways represented in the accretion ice and, by extension, in the lake. Approximately 94% of the sequences were from Bacteria and 6% were from Eukarya. Only two sequences were from Archaea. In general, the taxa were similar to organisms previously described from lakes, brackish water, marine environments, soil, glaciers, ice, lake sediments, deep-sea sediments, deep-sea thermal vents, animals and plants. Sequences from aerobic, anaerobic, psychrophilic, thermophilic, halophilic, alkaliphilic, acidophilic, desiccation-resistant, autotrophic and heterotrophic organisms were present, including a number from multicellular eukaryotes.

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 .…”

Abundance, viability and diversity of the indigenous microbial populations at different depths of the NEEM Greenland ice core

“…A recent report of Knowlton et al (2013) performed a 454 metagenomic/metatransciptomic analysis of two sections of the GISP2 ice core from 1601-and 3014-m depths yielding a limited number of 33 quality sequences unique to the ice. Several other metagenomic studies of glacial ice were performed on near surface glacial ice (Simon et al 2009;Choudhari et al 2013) or on subglacial Arctic ice and accretion Vostok ice (Hamilton et al 2013;Shtarkman et al 2013).…”

Earth as a Tool for Astrobiology—A European Perspective

“…Antarctic and Artic Ices A diverse set of microorganisms has been detected in the icesheet of the Lake Vostok in Antarctica (Priscu et al 1999;Karl et al 1999;Shtarkman et al 2013). The Artic permafrost has also a high content of microorganisms (Jakosky et al 2003;Gilichinsky et al 2003;Rivkina et al 2000;Vorobyova et al 1997;Vishnivetskaya et al 2006), making both environments good analogues for the icy Moons Europa, Enceladus and Ganymede.…”