Humans are leaving behind microbes on Mount Everest

South Col – a windswept, snow-free rocky dip located five miles above sea level in the Himalayan Mountains between Mount Everest and its sister peak Lhotse – is the place where hundreds of adventurers camp each year before attempting to climb the world’s largest peak from the southeastern side. 

According to a team of scientists led by the University of Colorado Boulder, they are also leaving behind a frozen legacy of highly resistant microbes that can survive harsh conditions at high elevations and lie dormant in the soil for decades or even centuries. While highlighting the invisible impact of tourism on the world’s highest mountains, these findings also provide a better understanding of the environmental limits to life on our planet, as well as in other places in the universe where life may exist. 

The scientists collected soil samples from South Col and analyzed them in several labs at CU Boulder by using both traditional culturing techniques and next-generation gene sequencing methods, in order to determine the diversity of microorganisms found in the samples. 

The analyses revealed that most of the microbial DNA sequences were similar to hardy, or “extremophilic” organisms previously detected in other high-elevation sites in the Antarctica or the Andes, with the most abundant organism being a fungus in the genus Naganishia, which is known to be able to withstand extremely high levels of cold and ultraviolet radiation. 

Surprisingly though, the experts also found microbial DNA of some organisms heavily associated with humans such as Staphylococcus, one of the most widespread skin and nose bacteria, and Streptococcus, a type of microbe usually infecting the human mouth. While the researchers were not surprised that humans left behind microorganisms – since microbes are nearly everywhere and can easily move around through the air at significant distances from camps or trails – they were nevertheless impressed by the fact that certain microbes which have evolved to thrive in warm and wet environments such as our noses and mouths are resilient enough to survive in a dormant state in the extremely harsh conditions from South Col. 

Although the impact of these microbes on the Himalayan environment is expected to be minimal, their presence there raises alarm for humans’ possible impact on extraterrestrial worlds that we may one day be able to travel to. “We might find life on other planets and cold moons. We’ll have to be careful to make sure we’re not contaminating them with our own,” concluded senior author Steven Schmid, a professor of Ecology and Evolutionary Biology at CU Boulder.

The study is published in the journal Arctic, Antarctic, and Alpine Research.

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By Andrei Ionescu, Earth.com Staff Writer

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