Evolution: how Archaea use hydrogen differently (Evolution)

by David Turell , Wednesday, June 12, 2024, 15:55 (162 days ago) @ David Turell

As the most ancient animal before oxygenation, itvis a logical finding:

https://www.sciencealert.com/third-form-of-life-makes-energy-in-remarkable-ways-scienti...

"...scientists have discovered that archaea – the third form of life after bacteria and eukaryotes – have been making energy using hydrogen gas and 'ultraminimal' enzymes for billions of years.

"Specifically, the international team of researchers discovered that at least nine phyla of archaea, a domain of single-celled organisms lacking internal membrane-bound structures, produce hydrogen gas using enzymes thought to only exist in the other two forms of life.

"Archaea, they realized, not only have the smallest hydrogen-using enzymes compared to bacteria and eukaryotes, but their enzymes for consuming and producing hydrogen are also the most complex characterized so far.

"Small and mighty, these enzymes have seemingly allowed archaea to survive and thrive in some of Earth's most hostile environments where little to no oxygen is found.

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"Microorganisms produce and release hydrogen gas (H2) for entirely different purposes, mainly to dispose of excess electrons produced during fermentation, a process whereby organisms extract energy from carbohydrates such as sugars without oxygen.

"Enzymes used for consuming or producing H2 are called hydrogenases, and they were first comprehensively surveyed across the tree of life only eight years ago. Since then, the number of known microbial species has exploded, particularly archaea, which hide out in extreme environments, such as hot springs, volcanoes, and deep-sea vents.

"However, most archaea are known only from chunks of their genetic code found in these environments, and many haven't been cultured in the lab because it's very difficult to do so.

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"But unlike bacteria and eukaryotes, further analyses showed that archaea assemble "remarkable hybrid complexes" for their hydrogen production needs, fusing two types of hydrogenases together.

"'These findings reveal new metabolic adaptations of archaea, streamlined H2 catalysts for biotechnological development, and a surprisingly intertwined evolutionary history between the two major H2-metabolizing enzymes," the team writes in their paper.

"Many of the cataloged archaea genomes analyzed in this study are, however, incomplete, and who knows how many more species are yet to be discovered.

"It's more than likely that archaea harbor other ingenious ways of making energy that we are yet to find."

Comment: as the most ancient form of life, it required these mechanisms to survive, using hydrogen as the available gas for 'respiration'.