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" Biogeochemical study of subglacial Lake Vostok accretion ice: searching for alien life in extreme conditions ".

Sergey Bulat

(Division of Molecular and Radiation Biophysics, Petersburg Nuclear Physics Institute, St. Petersburg-Gatchina, Russia)



The objective was to perform complex biogeochemical study of accretion ice of the subglacial Lake Vostok, East Antarctica with the ultimate goal to discover hidden life in this extreme icy environment. Principal analyses included gas content, dissolved organic carbon (DOC), major ion chemistry, mineralogy of sediments, microbial cell enumeration and 16S rRNA genes sequencing. As a result, total gas content proved to be 2-3 orders of magnitude lower than in glacier ice. Meanwhile a giant mica-clay sediment inclusion showed an unusual content of oxygen, carbon dioxide and methane. Mean DOC levels were found to be less than 20 pbb. Major ion chemistry showed enrichment of magnesium and calcium sulfates along with sulfides in ice with sediment inclusions only. Amongst the latter sulfide minerals like pyrite were also identified. Accordingly the possible redox couples are rather limited in supporting chemolithoautotrophic life forms. The molecular microbiology study constrained by Ancient DNA research criteria showed that the ice until depth 3659 m contains the very low microbial biomass. The present list of ice-indigenous findings comprises a few bacterial phylotypes including well-known chemolithoautotrophic (expected) thermophile (unexpected). Thus, the subglacial Lake Vostok can be unique in representing extremely nutrient and life poor giant aquatic environment.