A recent study conducted by the University of Colorado Boulder has revealed that tourists scaling Mount Everest, the world’s highest mountain, are unintentionally leaving behind a resilient microbial signature. The researchers discovered that microbes can withstand extreme conditions and remain dormant in the soil for decades or even centuries. The study found that even at high elevations, humans leave behind microbes that have evolved to thrive in warm and wet environments like our noses and mouths. However, most of the microbial DNA sequences they found were similar to hardy, or “extremophilic,” organisms previously detected in other high-elevation sites in the Andes and Antarctica. The researchers suggest that this microscopic impact on Everest would not significantly affect the broader environment but has implications for the potential for life far beyond Earth. Steve Schmidt, the senior author of the study, warns that we must take caution to ensure that we do not contaminate other planets and cold moons with our own microbes.
A recent study conducted by the University of Colorado Boulder has revealed that tourists scaling Mount Everest, the world’s highest mountain, are unintentionally leaving behind a resilient microbial signature. The wind-swept depression between Mount Everest and its neighboring summit, Lhotse, situated at an altitude of nearly five miles, remains barren and devoid of snow, but hundreds of thrill-seekers set up camp annually at the South Col to prepare for the final ascent from the southeast flank. Microbes left behind by humans can withstand the extreme conditions and remain dormant in the soil for decades or even centuries.
The study, published in the Arctic, Antarctic, and Alpine Research journal, indicates that the research could help better understand the environmental limits to life on Earth and where life might exist on other planets or cold moons. It could also spotlight the invisible impact of tourism on the world’s highest mountain. According to Steve Schmidt, a professor of ecology and evolutionary biology and senior author on the paper, there is a human signature frozen in the microbiome of Everest, even at that elevation.
The research used next-generation gene sequencing technology to analyze soil samples collected from such high elevation for the first time, which could provide new insights into the microorganisms left behind. Although the scientists expected to find human-associated microbes, they were impressed by certain microbes’ resilience, which had evolved to thrive in warm and wet environments like our noses and mouths. Such microbes could survive in dormant states even in such harsh conditions.
It is difficult to identify microbes from above 26,000 feet, and this study marks the first time that next-generation gene sequencing technology has been used to analyze soil samples from such a high elevation on Mount Everest. Microbes can be found everywhere, even in the air, and can quickly be carried away from nearby camps or trails. Even blowing the nose or coughing can leave traces of microbes. The study suggests that the findings could provide new insights into how life can adapt to extreme conditions, such as those on Mount Everest, and inform research on other planets or cold moons.
The cryobiosphere refers to Earth’s cold regions and the limits to life in them. A team of CU Boulder researchers, led by Steve Schmidt, including Nicholas Dragone and Adam Solon, both graduate students in the Department of Ecology and Evolutionary Biology and the Cooperative Institute for Research in Environmental Science (CIRES), study these cold regions, and the team has sampled soils everywhere from Antarctica and the Andes to the Himalayas and the high Arctic. However, human-associated microbes typically don’t appear in these areas to the extent they were discovered in the recent Everest samples.
Schmidt’s work over the years led him to researchers who were establishing the planet’s highest weather station in Everest’s South Col in May 2019, established by the National Geographic and Rolex Perpetual Planet Everest Expedition. Schmidt asked his colleagues to collect soil samples while they were there, and Baker Perry, co-author, professor of geography at Appalachian State University, and a National Geographic Explorer, hiked away from the South Col camp to collect soil samples to send back to Schmidt.
Dragone and Solon then analyzed the soil in several labs at CU Boulder using next-generation gene sequencing technology and traditional culturing techniques, enabling them to identify the DNA of almost any living or dead microbes in the soils. The researchers found microbial DNA for organisms heavily associated with humans, including Staphylococcus, one of the most common skin and nose bacteria, and Streptococcus, a dominant genus in the human mouth. However, most of the microbial DNA sequences they found were similar to hardy, or “extremophilic,” organisms previously detected in other high-elevation sites in the Andes and Antarctica.
At high elevations, microbes are often killed by ultraviolet light, cold temperatures, and low water availability, but only the hardiest critters survive. Most, like the microbes carried up great heights by humans, go dormant or die, but there is a chance that organisms like Naganishia may grow briefly when water and the perfect ray of sunlight provides enough heat to help them momentarily prosper. However, even for the toughest of microbes, Mount Everest is a Hotel California: “You can check out any time you like/ But you can never leave.”
The researchers do not expect this microscopic impact on Everest to have a significant impact on the broader environment. Still, this work has implications for the potential for life far beyond Earth if humans step foot on Mars or beyond.
The study conducted by the University of Colorado Boulder has highlighted the potential for life on other planets and cold moons. Steve Schmidt, the senior author of the study, warns that we must take caution to ensure that we do not contaminate other planets and cold moons with our own microbes. The research was funded by the National Geographic and Rolex Perpetual Planet Everest Expedition, the Department of Ecology and Evolutionary Biology, and the University of Colorado Boulder Libraries Open Access Fund.
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