During the Archean eon, approximately 3.4 billion years ago, the very first microbes utilized molybdenum—a metal that was exceedingly scarce at that time. These early life forms also experimented with tungsten. Researchers are hopeful that this information will aid in refining the approaches used by astrobiologists searching for extraterrestrial life.
Contemporary organisms display a significant reliance on molybdenum. However, during the early history of our planet, the oceans contained virtually no oxygen, rendering this metal inaccessible to microorganisms. This was the prevailing belief until recently.
Scientists previously operated under the assumption that life initially depended on tungsten and only later transitioned to molybdenum as it became more readily available. A team from the University of Wisconsin set out to test this prior notion. The findings of their investigation are detailed in the journal Nature Communications.
Molybdenum plays a critical role in the biogeochemical cycles involving carbon, nitrogen, and sulfur. Prior research had already established that many of these metabolic pathways originated in ancient times. In this new study, genomic databases were scrutinized to pinpoint organisms possessing the genes responsible for molybdenum transport, storage, and synthesis.
Employing a method of phylogenetic reconciliation, the scientists managed to reconstruct the evolutionary trajectory of proteins that incorporate both molybdenum and tungsten within the modern tree of life. Furthermore, the intracellular route taken by molybdenum—from uptake to catalytic function—was traced.
Concurrently, experts analyzed the historical utilization of tungsten in physiological processes. Ultimately, the team determined that despite its severe scarcity, terrestrial microbes somehow managed to find ways to employ it as far back as 3.3 to 3.7 billion years ago.
The authors believe this enhanced understanding will be valuable for astrobiologists searching for potentially habitable planets. For instance, over 20 organic compounds have already been identified on Mars…
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