Third form of life produces energy in 'remarkable' ways, scientists discover: ScienceAlert

As the world transitions to green hydrogen and other renewable energy sources, scientists have discovered that archaea – The third form of life After bacteria and eukaryotes – they have been producing energy using hydrogen gas and “radical” enzymes for billions of years.

Specifically, the international team of researchers discovered that at least nine phyla of AntiqueHydrogen, a domain of single-celled organisms that lack internal membrane-bound structures, produces hydrogen gas using enzymes thought to be present only in the other two forms of life.

They realized that archaea not only have smaller hydrogen-using enzymes compared to bacteria and EukaryotesBut its enzymes for consuming and producing hydrogen are also the most complex yet.

These small but powerful enzymes appear to have allowed archaea to survive and thrive in some of the most hostile environments on Earth where there is little or no oxygen.

“Humans have only recently begun to think about using hydrogen as an energy source, but archaea have been doing this for a billion years.” He says Bok Man Leung, a microbiologist at Monash University in Australia who co-led the study.

“Biotechnologists now have the opportunity to take inspiration from these archaea to produce hydrogen synthetically.”

Hydrogen is the most abundant element in the universe Used worldwide To make fertilizers and other chemicals, process minerals, process foods, and refine fuels.

But the future of hydrogen lies in energy storage and steelmaking, which can be produced without emissions If renewable energy is used To convert substances such as water into hydrogen gas.

Microorganisms Production and release of hydrogen gas (H₂) For completely different purposes, mainly to get rid of excess electrons produced during FermentationIt is a process in which organisms extract energy from carbohydrates such as sugars without oxygen.

Enzymes used to consume or produce H₂ Called Hydrogenaseand were surveyed comprehensively across the tree of life for the first time Only eight years ago. Since then, the number of known microbial species has increased dramatically, especially archaea, which hide in extreme environments, such as hot springs, volcanoes and deep-sea vents.

However, most archaea are known only from parts of their genetic code found in these environments, and many have not been cultured in the laboratory because it is too difficult to do so.

So Chris Greening, a microbiologist at Monash University, and his colleagues searched for the part that encodes the gene for one type of fast-acting hydrogenase. [FeFe] hydrogenase, in more than 2,300 archaeal species groups listed in a global database.

They then tasked Google's AlphaFold2 with predicting the structure of the encoded enzymes, and expressing those enzymes in… coli bacteria Bacteria, to confirm that these genes were indeed functional, produced hydrogenases capable of catalyzing hydrogen reactions in their surrogate host.

“Our findings bring us one step closer to understanding how this crucial process gave rise to all eukaryotes, including humans.” He says.

Eukaryotes are living organisms whose cells contain a nucleus and membrane-bound organelles, such as mitochondria and other useful cellular factories.

All eukaryotes are thought to have arisen from the union of anaerobic archaea with bacteria that devoured them billions of years ago. The second endosymbiosis, much later, gave rise to the ancestor of plants, with chloroplasts.

Greening, Leung and their colleagues found the genetic instructions for [FeFe] Hydrogenases in nine archaeal phyla confirmed that they are indeed active in those microorganisms, making them three of the three domains of life that use these types of enzymes to make hydrogen.

But unlike bacteria and eukaryotes, further analyzes showed that archaea assemble “exquisite hybrid complexes” to meet their hydrogen production needs, fusing two types of hydrogenases together.

“These results reveal new metabolic adaptations for archaea, simplifying H₂ Catalysts for the development of biotechnology, and a surprisingly intertwined evolutionary history between the two major H₂“Metabolic enzymes” team Write in their paper.

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

Archaea likely have other ingenious ways of producing energy that we have not yet discovered.

The research was published in cell.