They might not be visible to the human eye but according to researchers, a new group of climate-friendly microbes could be helping the planet in the carbon cycle. Living in hot springs, geothermal systems and hydrothermal sediments around the world, these microbes appear to be playing an important role in the global carbon cycle by helping break down decaying plants without producing the greenhouse gas methane.
A team of scientists from the US and China recently published findings from this research in the journal Nature Communications. The new group of microbes, which biologists call a phylum, is named Brockarchaeota after Thomas D. Brock, a pioneering microbiologist who discovered microbes and organisms that live in extreme environments such as the hot springs of Yellowstone National Park. A phylum is basically a broad group of related organisms.
Brock died on April 4. But his previous research led to a powerful biotechnology tool called PCR (polymerase chain reaction), which is used, among other things, in gene-sequencing and tests for covid-19. “Climate scientists should take these new microbes into account in their models to more accurately understand how they will impact climate change,” Brett Baker, assistant professor at the University of Texas at Austin's Marine Science Institute said in a news release. Baker, who led the research, said that the description of these new microbes from hot springs is a fitting tribute to Brock’s legacy in microbiology.
According to the release, Brockarchaeota have not been successfully grown in a laboratory or imaged under a microscope so far. They were identified by reconstructing their genomes from bits of genetic material collected in samples from hot springs in China and hydrothermal sediments in the Gulf of California, the release explains. “Baker and the research team used high-throughput DNA sequencing and innovative computational approaches to piece together the genomes of the newly described organisms,” the release adds. The scientists also identified genes that suggest how the microbes consume nutrients, produce energy and generate waste.
Valerie De Anda, the study’s first author, says there were genetic sequences going back decades, but none of them were “complete”. When the research team looked in public genetic databases, they found that these microbes had been collected all around the world but described as “uncultured microorganisms” -- referring to specimens collected by other researchers from hot springs in South Africa and Wyoming's Yellowstone, and from lake sediments in Indonesia and Rwanda. “So, we reconstructed the first genomes in this phylum and then we realized… they are around the world and have been completely overlooked,” De Anda adds.
Essentially, the Brockarchaeota are part of a larger, poorly studied group of microbes called archaea. Until now, scientists believed that the only archaea involved in breaking down methylated compounds -- that is, decaying plants, phytoplankton and other organic matter -- were those that also produced the greenhouse gas methane. “They are using a novel metabolism that we didn't know existed in archaea,” De Anda says in the release. “And this is very important because marine sediments are the biggest reservoir of organic carbon on Earth. These archaea are recycling carbon without producing methane. This gives them a unique ecological position in nature.”
Apart from breaking down organic matter, these newly described microbes have other metabolic pathways and De Anda speculates these might someday be useful in applications ranging from biotechnology to agriculture to biofuels.