Presence of Hydrogenophilus thermoluteolus DNA in accretion ice in the subglacial Lake Vostok, Antarctica, assessed using rrs, cbb and hox

Abstract

The 3561 m Vostok ice core sample originating from the subglacial Lake Vostok accretion (frozen lake water) ice with sediment inclusions was thoroughly studied by various means to confirm the presence of the thermophile bacterium Hydrogenophilus thermoluteolus reported earlier in the 3607 m accretion ice sample. PCR and molecular-phylogenetic analyses performed in two independent laboratories were made using different 16S rRNA gene (rrs) targeted primers. As a result, rrs-targeted PCR permitted to recover several very closely related clones with a small genetic distance to Hydrogenophilus thermoluteolus (< 1%). In addition, RubisCO (cbbL or rbcL) and NiFe-Hydrogenase (hoxV or hupL) targeted PCR have also allowed to recover sequences highly related to Hydrogenophilus thermoluteolus. All these results point to the presence of thermophilic chemoautotrophic microorganisms in Lake Vostok accretion ice. They presumably originate from deep faults in the bedrock cavity containing the lake in which episodes of seismotectonic activity would release debris along with microbial cells.

Searching for life in extreme environments relevant to Jovian’s Europa: Lessons from subglacial ice studies at Lake Vostok (East Antarctica)

“…Of these, one of the DNA signatures was of a (facultative) chemolithoautotroph Hydrogenophilus thermoluteolus, which proved to be a true thermophile (optimum temperature of +50 to 52°C) (Bulat et al, 2004). This finding for an accretion ice I sample from 3607 m depth was confirmed by another sample from 3561 m depth (Lavire et al, 2006). As the lake water temperature is at freezing point ($À2°C, because of the pressure), the niche for thermophiles should be outside the lake and probably at depth within the deep faults of the bedrock encircling the lake.…”

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

“…This has also been observed at Mount Spurr in Alaska [76]. A hydrothermal contribution to the Vostok subglacial lake (Antarctica) was suggested from bacterial gene analysis and the stable isotope composition of deep ice core samples [77,78]. If this emerging picture is correct, the deep waters of Lake Vostok could harbour an ecosystem fuelled by geochemical energy, much like that observed in deep-sea hydrothermal vent systems [19,79].…”

Interaction between ice sheet dynamics and subglacial lake circulation: a coupled modelling approach

“…Correspondence to: M. Thoma (malte.thoma@awi.de) been nurtured by microorganisms discovered in ice core samples (Karl et al, 1999;Lavire et al, 2006). These samples originate from the at least 200 m thick accreted ice, drilled at the Russian research station Vostok (Jouzel et al, 1999).…”