by Every year, hundreds of climbers camp at the South Col on the south side of Mount Everest in preparation for their attempt to reach the top of the world.
While these adventurers may take home some well-deserved bragging rights, a new study shows they may also be leaving behind some hardy microbes that seem able to bunker themselves to survive on the frigid, desolate outcrops.
Despite the extreme conditions on Everest, researchers have managed to cultivate bacteria and fungi isolated from the mountain’s sediments. These organisms, which are mostly dormant, may have been transported by wind or humans from less extreme terrain to the snow-free depression of the South Col.
This study shows the impact of tourists on the world’s highest peak and may shed light on the limits of life on Earth and the potential for life on other worlds.
Mount Everest (Sagarmatha in Nepali or chomolungma in Tibetan) is higher than any other land surface on Earth, peaking at 29,031 feet (8,849 meters) above sea level.
The altitudes of Everest are among the most extreme on earth. The South Col, where the research team led by University of Colorado Boulder (CU Boulder) microbial ecologist Nicholas Dragone collected soil samples, is about 7,900 feet above sea level.
So researchers were surprised to discover that even microbes that have adapted to the warm and humid comfort of our nose and throat, such as staphylococci And streptococcicould rest and survive the harsh, cold and dry conditions.
“Even at this altitude, a human signature is frozen in Everest’s microbiome,” says senior author Steven Schmidt, a microbial ecologist at CU Boulder.
“If someone even blew their nose or coughed, that could show up.”
In addition to traditional cultivation techniques that involve growing bacteria on nutrient-rich agar plates, the team sequenced slices of genetic material in the soil to identify specific microbes. It is reportedly the highest elevation in which such samples have ever been examined in this way.
Members of the team have previously examined soil samples from places like the Andes, as well as the Himalayas and Antarctica, but say this is the first time samples taken at this altitude have shown clear evidence of microorganisms associated with humans stand.
Higher levels of ultraviolet light, lower temperatures, and lack of water all contribute to the death of microbes at high altitude, allowing only the hardiest organisms to survive a hostile climate like this.
staphylococci And streptococci Bacteria are often found in soil, but the genetic sequences identified in this study were identical to those of common species that normally colonize our skin and mouth.
In addition, the samples were taken about 170 meters from where snotty, snuffling, sneezing people usually set up camp before accepting the summit challenge.
“We anticipate that we may find even more microbial evidence of human impact on the environment by sampling in the more heavily used areas of the mountain,” the team writes in their paper.
Most microbes, like those carried by humans to high altitudes, become dormant or die when exposed to such extreme conditions, but some organisms can grow at lofty altitudes during short periods of water availability, according to previous studies.
Because air temperatures at the South Col rarely rise above -10 °C (14 °F), it is not known whether the scarce water from melting ice can support microbial growth, and containing microbial growth in such extreme locations is no easy task testing.
So the ground on the South Col and other high places is only allowed to collect and freeze the organisms brought there by the air or by humans. The better conditions in the lab may have helped them grow.
However, air temperatures in the Mount Everest region are rising at about 0.33°C per decade, and in July 2022 the South Col recorded a record high of -1.4°C. This warming trend could cause organisms that are currently dormant to become active in the future.
The authors say the recently installed South Col weather station could provide more information and more observations over time.
At the moment, researchers don’t think this small addition of human germs to Everest will have a big impact on the environment. Nonetheless, this work has implications for the search for extraterrestrial life, for example if humans eventually reach Mars.
“Maybe we’ll find life on other planets and cold moons,” says Schmidt.
“We have to be careful not to contaminate them with our own.”
The study was published in the journal Arctic, Antarctic and Alpine research.
