Under the Surface: Microbial Life Beneath Earth's Surface Discovered

A team of scientists led by researchers at Bigelow Laboratory for Ocean Sciences has discovered a hidden world living beneath the Earth's surface, where organisms survive without oxygen. This discovery comes as a result of a method developed by the laboratory, linking the genetics and function of individual microbes. The study sheds light on the crucial role of microbial communities in global processes such as the carbon cycle.

New Approach Revolutionizes Understanding of Microbial Activity

The approach, developed at Bigelow Laboratory's Single Cell Genomics Center, allowed researchers to identify a species of sulfate-consuming bacterium as not only the most abundant but also the most active organism in a groundwater aquifer beneath Death Valley, nearly half a mile below the surface. Published in the Proceedings of the National Academy of Sciences, these findings are a step towards understanding the activity levels of organisms in extreme environments.

Lead author of the paper, Research Scientist Melody Lindsay, highlighted the importance of this discovery and said, "Previously, we had to assume that all cells were operating at the same rate, but now we can see that there is a wide range of activity levels between individual members of the microbial communities. That helps us understand what these microbial communities are capable of and how that might influence global biogeochemical cycles."

From Genomes to Phenomes: Decoding Microbial Activity

The study forms part of the larger "Genomes to Phenomes" project, a collaborative effort between Bigelow Laboratory, the Desert Research Institute, and the University of New Hampshire. Leveraging recent developments in single-cell genetic sequencing and flow cytometry, the project aims to bridge the gap between microbial genetics and their functional activities.

Flow cytometry, adapted from biomedical sciences, emerged as a key tool in this process, allowing researchers to analyze individual environmental microbes swiftly. By staining microbes with a specially designed compound, researchers could track chemical reactions within the cells, correlating fluorescence levels with the rates of these reactions. This technique was validated through lab-grown cultures of cells before being applied to samples from Death Valley.

Director of SCGC and principal investigator of the project, Ramunas Stepanauskas, said, "This study was an exciting opportunity for our research team and the SCGC to help improve our understanding of the immense, enigmatic microbial ecosystems underground."

Expanding Horizons: Future Applications and Implications

The research team is now exploring the application of their method in measuring other anaerobic reactions, such as nitrate reduction, and in diverse environments, including sediments along Maine's coast and the deep subsurface below the ocean. This research not only unveils the mysteries of life beneath the Earth's surface but also holds promise for potential applications on other planets.

Lead author Melody Lindsay stated, "Right now, we're getting all of these point measurements around the world, and they do help us better understand what microbes are up to, but we need to scale it up. So, we're thinking about how to apply this method in new places, even potentially on other planets, in expanded ways."

This research not only expands our understanding of life in extreme environments but also opens new avenues for exploration, both on Earth and beyond.