How our 2-billion-year-old microbial ancestors archaea made energy with hydrogen

Amazing stuff!

Will hydrogen become a viable alternative source of energy?

With hydrogen keep in mind: The Hindenburg Disaster of 1937! Hydrogen is dangerous, but human ingenuity will eventually learn to handle hydrogen safely.

"New research has redefined our understanding of how archaea – our 2-billion-year-old microbial ancestors – used hydrogen gas to produce energy. ...
There are 3 main domains of life on Earth: Eukarya, Archaea and Bacteria. ...
The team analysed the genomes of thousands of archaea and found they use unusual enzymes called [FeFe]-hydrogenases. Before this research, it was thought these enzymes were only produced by eukaryotes and bacteria.
And the archaeans’ hydrogen-using enzymes are the smallest and most complex. ..."

"... The findings, published today in Cell, explain how these tiny lifeforms make energy by consuming and producing hydrogen. This simple but dependable strategy has allowed them to thrive in some of Earth’s most hostile environments for billions of years. ...
The most widely accepted scientific theory also suggests that eukaryotes, such as humans, evolved from a very ancient lineage of archaea merging with a bacteria cell through exchanging hydrogen gas. ...

The team analysed the genomes of thousands of archaea for hydrogen-producing enzymes and then produced the enzymes in the lab to study their characteristics. They discovered that some archaea use unusual types of enzymes called [FeFe]-hydrogenases.

The archaea making these hydrogen-using enzymes were found in many of Earth’s most challenging environments, including hot springs, oil reservoirs, and deep beneath the seafloor. ..."

From the highlights and abstract:

"Highlights

• Archaea from nine different phyla encode structurally diverse [FeFe] hydrogenases

• Active ultraminimal [FeFe] hydrogenases are produced by uncultured DPANN archaea

• Ancient hybrid [FeFe] and [NiFe] hydrogenases are encoded by diverse archaea

• Hydrogen-producing Asgard archaeal cultures express [FeFe] hydrogenases

Summary

Microbial hydrogen (H2) cycling underpins the diversity and functionality of diverse anoxic ecosystems. Among the three evolutionarily distinct hydrogenase superfamilies responsible, [FeFe] hydrogenases were thought to be restricted to bacteria and eukaryotes. Here, we show that anaerobic archaea encode diverse, active, and ancient lineages of [FeFe] hydrogenases through combining analysis of existing and new genomes with extensive biochemical experiments. [FeFe] hydrogenases are encoded by genomes of nine archaeal phyla and expressed by H2-producing Asgard archaeon cultures. We report an ultraminimal hydrogenase in DPANN archaea that binds the catalytic H-cluster and produces H2. Moreover, we identify and characterize remarkable hybrid complexes formed through the fusion of [FeFe] and [NiFe] hydrogenases in ten other archaeal orders. Phylogenetic analysis and structural modeling suggest a deep evolutionary history of hybrid hydrogenases. 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."

How our 2-billion-year-old microbial ancestors archaea made energy with hydrogen

Scientists unlock secrets of how the third form of life makes energy (original press release)

Minimal and hybrid hydrogenases are active from archaea (open access)

Graphical abstract

Figure 1 Phylogenetically and metabolically diverse archaea encode [FeFe] hydrogenases

Strange, tentacled archaea microbe may resemble ancestor of complex life

Amazing stuff! The story of the origin of life on earth is not written yet not by a long shot! I think, we are still scratching only the surface! 😊

"By growing an unusual tentacled microbe in the lab, microbiologists may have taken a ... step toward resolving the earliest branches on the tree of life and unraveling one of its great mysteries: how the complex cells that make up the human body—and all plants, animals, and many single-celled organisms—first came to be. Such microbes, called Asgard archaea, have previously been cultured—once—but the advance reported today in Nature marks the first time they’ve been grown in high enough concentrations to study their innards in detail. ...
The resulting electron microscopy images reveal complex internal structures suggestive of those in our own cells, adding support to the still controversial idea that ancient Asgard-like microbes may have been the key ancestor of complex cells. ...
The idea that Asgard-like archaea might be the ancestors of eukaryotes came about in 2015 when ... discovered eukaryoticlike genes in strange archaea from sediment samples ...
But in 2019, ... team cultured the first Asgard microbe ... and reported that its genome also had eukaryotic genes.
Additional evidence came earlier this year [2022] when ... isolated enough of two other Asgard species ... to sequence their complete genomes. ...
The genes in those genomes bolstered the case that these genes really did arise in archaea. Moreover, the genomes harbored mobile pieces of DNA that contained bacterial genes involved in metabolism, suggesting these elements played a role in transferring genes among life’s major branches ...
but it took 12 years of trial and error to culture the first Asgard, and the second one described today wasn’t much easier. .. [a] 7-year project. ..."

From the abstract:

"Asgard archaea are considered to be the closest known relatives of eukaryotes. Their genomes contain hundreds of eukaryotic signature proteins (ESPs), which inspired hypotheses on the evolution of the eukaryotic cell. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated, but never visualized. Here we describe a highly enriched culture of ‘Candidatus Lokiarchaeum ossiferum’, a member of the Asgard phylum, which thrives anaerobically at 20 °C on organic carbon sources. It divides every 7–14 days, reaches cell densities of up to 5 × 107 cells per ml and has a significantly larger genome compared with the single previously cultivated Asgard strain. ESPs represent 5% of its protein-coding genes, including four actin homologues. We imaged the enrichment culture using cryo-electron tomography, identifying ‘Ca. L. ossiferum’ cells on the basis of characteristic expansion segments of their ribosomes. Cells exhibited coccoid cell bodies and a network of branched protrusions with frequent constrictions. The cell envelope consists of a single membrane and complex surface structures. A long-range cytoskeleton extends throughout the cell bodies, protrusions and constrictions. The twisted double-stranded architecture of the filaments is consistent with F-actin. Immunostaining indicates that the filaments comprise Lokiactin—one of the most highly conserved ESPs in Asgard archaea. We propose that a complex actin-based cytoskeleton predated the emergence of the first eukaryotes and was a crucial feature in the evolution of the Asgard phylum by scaffolding elaborate cellular structures."

Strange, tentacled microbe may resemble ancestor of complex life | Science | AAAS: Detailed internal images of second Asgard microbe reveal components similar to plant and animal cells

Actin cytoskeleton and complex cell architecture in an Asgard archaeon (open access)

Fig. 4: Complex and variable architecture of ‘Ca. L. ossiferum’ cells.