Scientists discover how ancient microbes use hydrogen for energy

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An international team of scientists has made a breakthrough in understanding archaea, a type of ancient microbe that is a distant ancestor of humans.

These microbes, which have existed for two billion years, have a unique way of making energy using hydrogen gas.

The findings were published in the journal Cell.

Archaea are single-celled organisms that thrive in some of Earth’s harshest environments, such as hot springs, oil reservoirs, and deep beneath the ocean floor.

They are one of the three main groups of life forms on Earth, alongside eukaryotes (which include animals, plants, and fungi) and bacteria.

The study, led by scientists from Monash University’s Biomedicine Discovery Institute, including Professor Chris Greening, Professor Jill Banfield, and Dr. Bob Leung, reveals how archaea produce and consume hydrogen to generate energy.

This simple but effective strategy has allowed them to survive in extreme conditions for billions of years.

Dr. Bob Leung explained that understanding how these ancient microbes use hydrogen could also benefit humans, especially in developing new ways to use hydrogen for clean energy.

“Humans have only recently started exploring hydrogen as an energy source, but archaea have been using it for a billion years. We can learn from them to produce hydrogen in environmentally friendly ways,” said Dr. Leung.

The researchers analyzed the genomes of thousands of archaea to identify enzymes that produce hydrogen. They discovered that some archaea use unique types of enzymes called [FeFe]-hydrogenases.

These enzymes were previously thought to exist only in eukaryotes and bacteria. This study is the first to show that archaea also have these enzymes, and they come in a variety of forms and functions.

The team produced these enzymes in the lab to study their properties. They found that some archaea have the smallest hydrogen-using enzymes known, while others have the most complex ones. These findings could help develop more efficient and resilient methods for industrial hydrogen production.

Professor Chris Greening highlighted the potential applications of these discoveries in transitioning to a green economy. “Currently, industry uses expensive chemical catalysts for hydrogen production. Nature shows us that biological catalysts can be highly efficient and robust. We could use these biological catalysts to improve hydrogen usage,” he said.

The study also provides insights into the evolution of life on Earth. The most widely accepted scientific theory suggests that eukaryotes, such as humans, evolved from a very ancient lineage of archaea merging with a bacterial cell through the exchange of hydrogen gas. “Our finding brings us closer to understanding how this crucial process gave rise to all eukaryotes, including humans,” added Dr. Leung.

With their ancient origins and potential applications in biotechnology, archaea continue to fascinate researchers and hold promising avenues for further discovery and practical use.