In a NASA study, the microorganism Bacillus subtilis survived six years in the vacuum and cold of space.
Credit: NASA
EAST LANSING: New research sheds light on how microorganisms are able to 'hibernate' for long periods of time. This unique ability affects entire ecosystems on Earth, and could have implications for the transport of organisms between planets.
It’s commonly known, at least among microbiologists, that microbes have an additional option to living or dying - dormancy. What isn’t known, however, is how large numbers of dormant microorganisms affect the natural environments when they act as microbial seed banks.
“Only a tiny fraction is metabolically active at any given time,” said lead author Jay Lennon, who is affiliated with Michigan State University’s (MSU) Kellogg Biological Station and MSU’s AgBioResearch. “How would our environment be altered, in terms of carbon emissions, nutrient cycling and greenhouse gases such as nitrous oxide, by dramatic increases or decreases in the dormancy of microbes?”
Identifying past and present martian life
The ability of microorganisms to remain dormant for long periods of time is relevant to studies concerning the transfer of organisms from one planet to another, either by natural means or on spacecraft sent by humankind.
Dormant microorganisms can also teach us about signatures that could identify past or present life on other planets, such as Mars.
In the current issue of Nature Reviews: Microbiology, Lennon, an assistant professor of microbiology and molecular genetics at MSU, examines the cellular mechanisms that allow microbes to hibernate and addresses the implications they can have on larger ecosystems such as soil, oceans, lakes and the human body.
Waiting for the truly hard times
Dormancy is a reversible state of low metabolic activity that organisms enter when they encounter hard times, such as freezing temperatures or starvation. Unlike plants that follow predictable growth cycles, microbes don’t have to follow a linear progression.
They could be growing, experience distress and go back to sleep. Once conditions change, they could start growing again without having to go through a full cycle.
“However, it does take a certain level of commitment, a certain energy investment to make it happen,” Lennon said. “Just as people don’t run out and winterise their homes if it gets cool at the end of summer, microbes want to be sure that truly hard times have set in before shifting into a dormant phase.”
