Microbial Trancsriptomic response to thawing and freezing of active layer permafrost soil
Morten Schostag, PhD student, CENPERM/BIO
Permafrost affected soil systems represent 17% of the global land area. Due to increasing global temperature the thickness of the above-lying active layer has increased over the past decades. The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which we hypothesize to affect microbial activity. To be able to survive these conditions microbes have different survival mechanisms, such as lipid modification to maintain cell membrane fluidity, antifreeze proteins to inhibit formation of ice crystals, and cold adapted enzymes with high specific activity at low temperatures. Most of these mechanisms have been identified and verified in pure cultures of microbes isolated from cold environments but very little is known about the mechanisms employed by soil microbial communities. Thus, we investigated the microbial responses upon thawing and again during freezing of active layer permafrost from Svalbard.
Microbial responses were investigated by incubating active layer soil at 4 oC intervals from -10 to 2 oC over 6 days. Two and a half weeks at 2 oC were followed by freezing at 4 oC intervals to -10 oC over 6 days. Metatranscriptomic data were obtained by extracting RNA from 2 gram of soil sample and sequencing it using Illumina Hiseq 150 bp paired-end technology. Sequences were Blasted against the non-redundant protein database from NCBI.
I will present our preliminary result, showing the dominant responses of active layer soil microorganisms upon thawing and freezing at different temperatures.
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