In the late 1970s, a new branch was added to the tree of life, and archaea joined bacteria and eukarya, as domain classifications. Archaea and bacteria are both simple forms of cells called prokaryotes, and they contain complexes and macromolecules but no membrane-bound organelles, like those found in the eukaryotic cells that make up plants and animals. Some studies have suggested that the original ancestors of complex life forms including humans are archaea.
Scientists have now outlined how archaea use hydrogen gas to make energy, which has allowed these ancient organisms to survive in some of the most inhospitable places on Earth for billions of years. The findings have been reported in Cell, and they could help us develop new approaches for using hydrogen as an energy source, suggested study co-author Dr. Bob Leung of Monash University.
"Humans have only recently begun to think about using hydrogen as a source of energy, but archaea have been doing it for a billion years. Biotechnologists now have the opportunity to take inspiration from these archaea to produce hydrogen industrially," said Leung.
In this work, the researchers analyzed archaeal genomes, searching for enzymes that could produce hydrogen. Once they identified those genes, they recreated the enzymes encoded by those genes in the lab, and studied them. One unusual type of enzyme was found, called [FeFe]-hydrogenases; they are made by some archaea that live in very extreme environments like oil reservoirs and hot springs.
It has been thought that these hydrogenase enzymes were only made by bacteria and eukaryotes. This works has challenged those assumptions, however, by revealing complex and tiny hydrogenases produced by archaea. This enzymes might be useful to us, too.
Right now, hydrogen is used with critical chemical catalysts in industrial applications. But we also know that the function of natural catalysts can be very efficient and durable, noted first study author Professor Chris Greening of Monash University. "Can we use these to improve the way that we use hydrogen?"
"Our finding brings us a step closer to understanding how this crucial process gave rise to all eukaryotes, including humans," Leung added.
Scientists seem to be only starting to reveal some of the amazing characteristics of archaea, ancient microbes that could turn out to be our ancestors.
Sources: Monash University, Cell