Glacier ice core reveals microbes 15,000 years ago

Glacier ice core reveals microbes 15,000 years ago

Known as the world “Third Pole”, The Qinghai-Tibet Plateau has a large amount of earth ice.More than 46,000 glaciers cover the arid highland landscape, which is vast Hindu Kush Himalayas (HKH) Mountains.These mountains and their ice sheets are jointly owned The largest amount of snow and ice outside the Arctic and AntarcticConsidering that it descends to ancient and inaccessible depths, one might easily assume that ice is sterile and lifeless except for its inert ingredients. However, a new survey of the ice cores of Tibetan glaciers reveals the opposite: These huge glaciers actually have a rich chronological record of frozen, unique microbial life.

Zhong Zhiping is a postdoctoral researcher in paleoclimatology at Ohio State University Bird Polar and Climate Research Center, And a lead author New publication In the magazine Microbiome An overview of his team’s investigation of nearly 15,000-year-old microbes in the hidden ice. Their innovation lies in their method-as we all know, it is difficult to isolate and preserve ancient microbial DNA well to analyze individual genomes while avoiding sample contamination or degradation. In addition, the biomass level of glacier ice is very low, which makes today’s microbial and virus contamination a greater risk. Zhong and his team pioneered a new method to accomplish this difficult task with extraordinary precision, allowing them to see ancient genes.

“We have developed a cleaning method to remove Pollutants On the surface of the glacier ice core,” Zhong explained in an interview with GlacierHub. “This helps ensure that we get the’real’ microbes and viruses archived in the glacier ice, not contaminants. “The team’s method includes meticulous scraping and disinfection of the core until the innermost ice layer, separating relatively uncontaminated material for analysis. They extended their previous work and first verified that they were on an artificial core. The method of adding known bacteria allowed them to measure the amount of simulated pollutants remaining. With more specific data on the effectiveness of their method, they began to clean and process the actual core.

The ice core used in the investigation was drilled from the Gulia Ice Cap in 2015 by Lonnie Thompson and colleagues. Thompson is a well-known paleoclimatologist and has been a professor at Ohio State University since 1991. He started (together with Alan Mosley-Thompson) a few decades ago to build the ice core of the Byrd Polar and Climate Research Center collect. Zhong emphasized that glacial ice not only records the past climate and chemical information of the earth’s atmosphere, but also records the entire microbial ecosystem, providing a preserved biological record that dates back thousands of years.

A culture of Sphingomonas, a genus of bacteria found to be frozen in ancient ice cores.
source: Nathan Redding

The research team’s careful prevention and reduction of pollution methods both inside and outside the laboratory revealed certain bacterial groups commonly found in glacier ice, such as Janthinobacterium, Polaromonas and SphingomonasHowever, an investigation of the genetic material of the virus revealed a complete gene sequence unique to the study, revealing 28 new genera. The rate of 88% of new genera found in glacial ice is much higher than the rate found by virus analysis of the marine environment.52% unique genera) And soil (61% unique genera). Such extraordinary discoveries in details are indispensable to Zhong’s research goals. He explained that he hopes to understand the mutation rate of microorganisms over a long period of time by comparing the frozen genome with the genomes of more current bacteria and viruses. “These efforts will make it possible for us to use some kind of molecular clock to help determine the age of ice.”

Potential applications of the clock. The method of waiting will not end on this planet. Extreme life Creatures on Earth (including hardy ice bacteria and other microorganisms) are often studied as potential models for extraterrestrial life on other planets and moons.There are many celestial bodies in our solar system Port water ice, Although in more extreme climatic conditions, leading to Astrobiology Hypothesis Such ice may be enough to provide livable conditions for life. Since the team’s agreement was developed to extract microbes and viruses from high-altitude, cold and dry environments on Earth, Zhong pointed out that similar technologies “may one day be applied to search for life in the polar regions of Mars and other icy environments. “. The world in our solar system. ”

These technologies are expected to expand our understanding of microbial history and evolution, but with the emergence of this field, the existential threat of climate change will follow.A quarter of the third pole has Melted since 1970And according to 2019 Report of the IPCC, It is estimated that two-thirds of its glaciers will disappear in the next 80 years. These catastrophic trends are global to varying degrees. With the melting, the biological history of the earth can be traced back hundreds of thousands of years. As these records transition to the melting water, they cannot be saved.

Shelves of Byrd Polar and Climate Research Center.
source: James St. John

Recognizing this threat, the Bird Center for Polar and Climate Research has collected and preserved more than 7,000 meters of ice core in its 40-year global glacier ice analysis.this Freezer in the Bird Center It is a time capsule that preserves the history of the world, and soon may not be accessible anywhere else. Archived ice cores and clock methods can be used as the basis for the next generation of researchers. The only landscape in a once magnificent and biologically rich glacier is to work in shelving icicles, each four inches wide, about yards. long. Scientists have only just begun to read the vast array of genetic books contained in Earth’s glaciers—these new methods of restoring frozen genomes and protecting the threatened ice layer are now facing a fruitful and deadly race against time.