Deep biosphere microbes expand the chemical signatures of life

phys.org | 6/27/2018 | Staff
madalina09madalina09 (Posted by) Level 4
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Search for signs of ancient microbial life in the geological record is challenging due to degradation of the primary organic material. Therefore, proof of biogenic origin often relies on chemical signatures that microorganisms leave behind. A new study of minerals in rock cracks presents chemical signatures that are definite proofs of widespread ancient life processes in the energy-poor continental crust. More importantly, the study greatly expands the known chemical variation of sulfur, one of the key elements in microbial metabolisms. This gives new clues to what type of chemical signatures to expect from life in extreme environments, including search for life on other planets.

A major part of the biologic activity on Earth is hidden underneath the soil down to depths of several kilometres in an environment coined the "deep biosphere". Studies of life-forms in this dark anoxic system have implications for how life has evolved under conditions we consider extreme. It also gives clue to how life may have evolved on other planets where hostile conditions inhibit colonization of the surface environment. The knowledge about ancient life in this environment deep under our feet is still extremely scarce.

Search - Signs - Life - Earth - Record

Search for signs of ancient life on Earth in the geological record is often challenging because the primary organic material has been partially or completely degraded. In these situations, the proof of biogenic origin relies on geochemical signatures that microorganisms leave behind, or to morphological shapes of mineralized microbial remnants. In search for life on other planets, such as on Mars, the same challenges can be expected and it is therefore important to know what type of chemical signatures to expect from life in extreme environments.

In numerous cracks down to depths of 1700 meter that have been partly sealed by crystals grown in them, a team of researchers led by Dr. Henrik Drake...
(Excerpt) Read more at: phys.org
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