Professor Magdalena Osburn removed the samples during a site visit in August.

A former gold mine serves as a gateway to explore microbes deep within the Earth’s crust. If you add up the mass of all the microorganisms that live beneath the Earth’s surface, their combined biomass exceeds the biomass of all life in the oceans. However, because of the difficulty of accessing these depths, this myriad of subterranean organisms remains largely unexplored and poorly understood. Using a repurposed gold mine in the Black Hills of South Dakota as a laboratory, Northwestern University researchers have created the most comprehensive map yet of the elusive and rare microbes that live beneath our feet. In total, the researchers characterized nearly 600 microbial genomes, some of which were new to science. Within this group, most microbes fit into one of two categories, said Magdalena Osburn, a Northwestern geoscientist who led the study. And “maximalists” are ready to greedily grab any resources that may come their way. This study was recently published in the journal environmental microbiology.

This new research not only expands our knowledge of the microbes that live deep underground, but also hints at potential life that may one day be discovered underground. Mars. Because microbes rely on resources in rocks and water that are physically distant from the surface, these organisms could survive buried in Mars’ dusty red depths. “The deep underground biosphere is huge. It’s just a huge space,” said Osburn, an associate professor of Earth and planetary sciences in Northwestern University’s Weinberg College of Arts and Sciences. “We used the mine as a conduit to access a biosphere that is difficult to reach no matter how we approach it. A lot of that comes from understudied groups. DNA, you can understand what kind of creatures live underground and find out what they do. These are organisms that we cannot grow in the laboratory or study in more traditional settings. They are often referred to as “microbial dark matter” because we know so little about them.

For the past 10 years, Osburn and his students have been regularly visiting the former Homestake Mine in Reed, South Dakota, collecting geochemical and microbial samples.Now Sanford Underground Research Facility (SURF)’s deep underground laboratory is home to numerous research experiments across a variety of fields. In 2015, Osburn established his six proving grounds. Mine Deep Microbial Observatorythroughout SURF.

Back in Osburn’s lab at Northwestern University, she and her team sequenced the DNA of the microorganisms held within the samples. Of the approximately 600 genomes characterized, microorganisms represented 50 different phyla and 18 candidate phyla. Osburn discovered that within this diverse microbial community, each lineage, at some point, gravitates toward a life-defining trajectory: becoming a minimalist or a maximalist.
“Some of these strains don’t even have the genes to make their own lipids, which is shocking,” Osburn said. “Because how can you make cells without fat? It’s like humans can’t make all the amino acids. Therefore, by consuming protein, amino acid Something we can’t create on our own. But this is on a more extreme scale. Minimalists are the ultimate specialists and we all work together. There’s a lot to share and no duplicate work

Osburn said these underground microbes may provide clues to what might exist elsewhere as we imagine life beyond Earth. “It’s really exciting to see evidence of microbes operating without us, without plants, without oxygen, without surface atmosphere,” she said. “It’s very likely that this kind of life currently exists deep on Mars or in the icy moon’s oceans. The forms of life tell us what lives elsewhere in the solar system.”
And they also affect our own planet. For example, as industry looks for long-term storage for carbon, many companies are exploring the possibility of injecting it deep underground. As we consider those options, Osburn reminds us not to forget the microbiome.

Reference: “A Metagenomic View of New Microbial and Metabolic Diversity Discovered in the Earth’s Deep Biosphere in DeMMO: Microbial Observatory in South Dakota, USA” by Lily Momper, Caitlin P. Casar, and Magdalena R. Osburn, 2023. November 14th, environmental microbiology.DOI: 10.1111/1462-2920.16543 This research was supported by NASA Exobiology (grant numbers NNH14ZDA001N, NNX15AM086), the David and Lucille Packard Foundation, and the Canadian Institute for the Advancement of Research—Earth 4D.

Source: scitechdaily.com