New Discovery of Microbes Gobbling Up Greenhouse Gases in Extreme Environments

Hot springs are a hotspot for microbial ecologists. Microbes lurk in the bubbling, steaming, and highly sulfuric liquid. These microbes are capable of surviving the most extreme environments, for this reason, we call them ‘extremophiles.’ One of the pioneers of extremophile research was Dr. Thomas Brock, who isolated bacteria that survive the super scalding temperatures of the hot springs in Yellowstone National Park. The microbes he discovered were integral in the development of the PCR testing which aided COVID-19 testing around the world.

Geothermal springs like those found in Yellowstone National Park are home to many different species of extremophiles, microbes that thrive in extreme environments like those with high heat and chemical stress. Source: Creative Commons.

Since the pioneering microbiology by Brock, scientists have been probing hot springs for more microbial life and recently, a group of scientists discovered an entirely new phylum of Archaea. Archaea are different from bacteria and are in their own Kingdom (the other kingdoms are Bacteria and Eukaryotes — which contains all the plants and animals). To put this into perspective, humans are in the phylum Chordata which contains about 43,000 species so there may be thousands of species in this new phylum waiting to be discovered!

This new phylum, Brockarchaeota, was named after Brock to commemorate his insights into microbiology.

This is a generalized depiction of the three domains and some of the many phyla. Brockarchaeota will be added as another arm in the Archaea domain. Source: Wikimedia Commons.
DNA Technologies Led to New Discoveries

It can be difficult to discover new microbes because they are tiny, incredibly diverse, and many are difficult to grow in the lab. One way to get around these variables is by using DNA sequencing which allows researchers to “see” the microbes in an environmental sample, the majority of which have never been grown in the lab or observed under a microscope. In this study, the scientists found pieces of DNA from a bunch of different microbes and by piecing the DNA fragments like a puzzle, they could assemble genomes for individual species. Once scientists complete the DNA puzzle, they have the information they need to understand what microbes are there and what they are doing by looking at the individual genes.

Geothermal vents in the ocean are very hot and are host to a variety of ocean extremophiles. Source: Creative Commons.

In total, researchers found fifteen microbial genomes by assembling the DNA puzzle pieces from hot springs in Tibet and China and underwater thermal vents in the Bay of California. Then, they searched the genome databases for similar genomes that may also be Brockarchaeota. From this information, they discovered that many of the unknown DNA sequences other researchers found are similar to their Brockarchaeota genomes, suggesting that this new phylum is found in hot springs and geothermal environments around the world! The researchers then used the information in the DNA to predict that proteins these organisms make and consequently, infer the role they play in the ecosystem. Microbes are important for cycling nutrients like carbon and nitrogen around the world and can act as sources of carbon and sinks, which are integral in slowing climate change.

Tiny Microbes Play Huge Roles in the Carbon Cycle

There is still a lot we don’t know about microbes in these extreme environments but through computational tools and genomic databases the researchers predict that this phylum is important in the global carbon cycle.

For example, in environments where there is little to no oxygen, these organisms can degrade complex carbon compounds without producing methane, a potent greenhouse gas. Often when microbes degrade these compounds, they produce methane which adds to the growing greenhouse gases in the atmosphere. By degrading these compounds without producing methane, these microbes are recycling carbon without adding to climate change.

This figure from the original journal article shows how the researchers expect Brockarcheota to work in the carbon cycle. Looking past the complexity, the general idea is that Brockarcheota eat up methane and other carbon compounds without releasing any more carbon into the atmosphere. Creative Commons Attribution 4.0.

The researchers suggest the activity of this phyla should be included in future global carbon cycle models which track the sources and sinks of carbon around the world.

Finally, like all new discoveries, there is an untapped potential in this biodiversity. The authors speculate that these microbes may have applications in agriculture or biofuels. It is astounding that in a world where humans feel like they dominate, there is hidden biodiversity in every nook and cranny, just waiting to be discovered. The namesake of this new phyla, Dr. Brock, passed away on April 4, 2021 but his legacy lives on, inspiring new generations of microbial ecologists.

Source:De Anda, V., Chen, LX., Dombrowski, N. et al. Brockarchaeota, a novel archaeal phylum with unique and versatile carbon cycling pathways. Nat Commun 12, 2404 (2021). https://doi-org.libproxy.sdsu.edu/10.1038/s41467-021-22736-6

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Brianne Palmer

I am a PhD candidate at San Diego State University and the University of California, Davis studying how biological soil crusts respond and recover from fire. Most of my research is in coastal grasslands and sage scrub. We use DNA and field measurements to understand how cyanobacteria within biological soil crusts help ecosystems recover after low severity fires. I am also involved with local K-12 outreach within the Greater San Diego Metro Area.

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