Researchers have found some of the oldest and slowest life forms on Earth:
In a bid to hone in on the lower energy limits for life, Hans Røy at Aarhus University in Denmark probed the clays below the North Pacific gyre. Under the microscope, he found a community made up of bacteria and single-celled organisms called archaea in vanishingly small numbers.
“There are only 1000 tiny cells in 1 cubic centimetre of sediment, so finding just one is literally like hunting for a needle in a haystack.”
The microbes rely on oxygen, carbon and other nutrients in their deep environment to live, but Røy’s team found that carbon is so limited that the cells respire oxygen 10,000 times slower than bacteria in lab-grown cultures.
Røy thinks the microbial community is so sparse, and the metabolic rates so low, that the nutrient levels probably represent the bare minimum required to keep cellular enzymes and DNA working. “It looks like we have reached the absolute lower limit for the metabolism of cells,” he says.Colin Barras, “Buried microbes exist at limit between life and death” at New Scientist
Some of the cells may be thousands of years old, he thinks, which is practically living forever in cell terms.
Study of such extreme cells might shed light on the constraints and tradeoffs of life, now and in the past, and possibly elsewhere in the universe.
See also: Light-loving cyanobacteria found, improbably, nearly 2,000 feet underground
Life form found at abyssal depths
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