New research discovers surprising activity among organisms thriving in extremely deep, hot subseafloor
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"We propose that the organisms are forced to maintain a high metabolic turnover, which approaches the activity of microbes living in surface sediments and in laboratory cultures, to provide the energy required to repair thermal cell damage," said Felix Beulig from the University of Bayreuth, who is the lead author of the study. "The energy required to repair thermal damage to cellular components increases steeply with temperature, and most of this energy is likely necessary to counteract the continuous alteration of amino acids and loss of protein function," said the study leader, Tina Treude, UCLA professor of marine geomicrobiology.
It is far from trivial to detect microbial metabolic activity in sediments with less than 500 cells per cubic centimeter sediment, which is seven orders of magnitude lower than in the average surface sediment. "We worked under extremely controlled, sterile conditions and performed a large number of control experiments simultaneously with the sample incubations," said Florian Schubert from the German Research Centre for Geosciences, who conducted these analyses as part of his Ph.D. studies. "We even incubated sediment sterilized with high gamma radiation, as well as drill fluid from the drill hole, to detect any potential non-biological reactions or contamination-induced microbial activity," said Jens Kallmeyer, who is the mentor of Florian Schubert."
https://phys.org/news/2022-01-extremely-deep-hot-subseafloor.html