The newly awakened microbe Herminiimonas glaciei may contain clues to past climatic conditions on Earth - and even life on other planets.
Credit: Society for General Microbiology
SYDNEY: A new species of bacterium, found three kilometres deep in Greenland's glacial ice, has survived 120,000 years of freezing.
Named Herminiimonas glaciei, the microbe may contain clues to past climatic conditions on Earth, said Jennifer Loveland-Curtze, an astrobiologist from Pennsylvania State University in the U.S., and lead researcher behind the discovery.
"Ultra-small microbes are found in many environments, but very few have been studied. Glacier isolates such as H. glaciei may provide insights into how cells can survive, grow and metabolise under extremely harsh glacial conditions," she said.
Novel organism
Loveland-Curtze led a team that details the discovery in the International Journal of Systematic and Evolutionary Microbiology.
By some estimates, microbial cells make up the majority of the mass of all life on Earth, playing an important role in natural processes, such as carbon cycling. Only a small fraction of bacteria have ever been studied, however. This is because most can't be grown in a lab.
"Although DNA studies of glacial samples have detected many novel organisms, only 15 new species have been officially described," Loveland-Curtze told Cosmos Online. Official description requires a rigorous laboratory analysis of a microbe's metabolism, appearance, and genetics.
Coaxed out of dormancy
The researchers suspected that bacteria trapped in glacial ice might be difficult to culture because they are in a dormant, inactive state. They tested this theory on a melted section of ice core drilled from one of Greenland's glaciers. The ice was from a depth of three kilometres, making it around 120,000 years old.
After capturing any organisms in the melted ice with an ultra-fine filter, they coaxed the bacteria back to life by incubating them in an oxygen-free solution at just above freezing – first at 2°C for seven months and then at 5°C for four and a half months.
"A brownish-purple colony, comprised of millions of identical bacterial cells, was then visible," said Loveland-Curtze. Genetic analysis suggested they had found a new species – the bacteria's purple colour and dislike of oxygen clinched the case.
Able to survive in limited space, with almost no nutrients, under high pressure at a shockingly low -56°C, this new species is undoubtedly unique, she said.
By unlocking the secrets to its success, the researchers hope to learn more about how life adapts to severe climates. "Glaciers provide the best records of past climates. The quantity and types of organisms deposited during different periods depends on the corresponding climate conditions," said Loveland-Curtze.
"These extremely cold environments are [also] the best analogues of possible extraterrestrial habitats," she added, and could give us clues of how to recognise alien life.
Staggeringly small
H. glaciei is staggeringly small, even by bacterial standards. 50 times smaller that E. coli, it can easily pass through standard sterilisation filters used in hospital. The researchers are quick to point out, however, that H. glaciei doesn't cause disease. They think its small size may help it inhabit niche environments by allowing it to take up nutrients efficiently.
Brent Christner, a microbiologist from Louisiana State University in Baton Rouge, is impressed. "We've been studying bacteria preserved in ancient ice for over a decade, and although we know these bugs can persist for extended time frames in ice, we still don't know how they do it," he said.
Christner, who was not involved in the research, said that the work may be a first step towards determining the traits that allow these microbes to survive frozen for millennia.
Follow Cosmos on Twitter!
twitter.com/cosmosmagazine
