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

Abstract

Abstract:Since the first descriptions of Antarctic subglacial lakes, there has been a growing interest and awareness of the possibility that life will exist and potentially thrive in these unique and little known environments. The unusual combination of selection pressures, and isolation from the rest of the biosphere, might have led to novel adaptations and physiology not seen before, or indeed to the potential discovery of relic populations that may have become extinct elsewhere. Here we report the first microbiological analysis of a sample taken from a former subglacial lake sediment in Antarctica (Lake Hodgson, on the Antarctic Peninsula). This is one of a number of subglacial lakes just emerging at the margins of the Antarctic ice sheet due to the renewed onset of deglaciation. Microbial diversity was divided into 23.8% Actinobacteria, 21.6% Proteobacteria, 20.2% Planctomycetes and 11.6% Chloroflexi, characteristic of a range of habitat types ( Overall, common sequences were neither distinctly polar, low temperature, freshwater nor marine). Twenty three percent of this diversity could only be identified to -unidentified bacterium‖. Clearly these are diverse ecosystems with enormous potential.

Untitled

“…After 16 months of simulated warming, a net decrease of Proteobacteria, Acidobacteria, and Planctomycetes were observed across all three soil samples indicating that they were highly affected by increased temperature. The results agree with previous studies by Mateos-Rivera et al (2016), Pearce et al (2013), and Schuette et al (2010) that stated Proteobacteria decreases with higher incubation temperatures. Skidmore et al (2005) suggested that Proteobacteria decreases with increasing temperature, as some of the members are adapted to live in lower temperature habitats with low organic matter content.…”

Actinobacteria from Arid and Desert Habitats: Diversity and Biological Activity

“…Actinobacteria from a low water activity area of Antarctica (similar to the situation in deserts) are also described. The bacterial diversity of Lake Hodgson, the Antarctic Peninsula, was recognized as 23% Actinobacteria , 21% Proteobacteria , 20.2% Plantomycetes , and 11.6% Chlorofllexi (Pearce et al, 2013 ), while from Antarctic Dry Valley soil Cyanobacteria (13%), Actinobacteria (26%), and Acidobacteria (16%) represented the majority of the identified resident bacteria (Smith et al, 2006 ). Culture-independent survey of multidomain bacterial diversity in the cold desert of the McKelvey Valley demonstrated that highly specialized communities colonize in distinct lithic niches occurring concomitantly within this ecosystem.…”

Physical and chemical controls on habitats for life in the deep subsurface beneath continents and ice

“…Grímsvötn Lake yields bacterial cell counts of approximately 10 4 per millilitre under 300 m of ice [ 42 ]; Skaftárketill Lake yields up to 5×10 5 bacterial cells per millilitre [ 43 ]. High cell densities have been found in subglacial sediments in several other regions, including the Alps [ 44 ], New Zealand [ 45 ], the Canadian High Arctic [ 46 ], Svalbard [ 47 ], the Antarctic Peninsula [ 48 ] and the West Antarctic Ice Sheet [ 37 ].

Figure 3.

…”