Natures wonders: immortal bacteria (Introduction)

by David Turell , Saturday, March 06, 2021, 14:54 (1356 days ago) @ David Turell

100 million years old and still alive:

https://www.scientificamerican.com/article/100-million-year-old-seafloor-sediment-bacte...

"In 2010, Japanese scientists from the Integrated Ocean Drilling Program’s Expedition 329 sailed into the South Pacific Gyre with a giant drill and a big question.

"The gyre is a marine desert more barren than all but the aridest places on Earth. Ocean currents swirl around it, but within the gyre, the water stills and life struggles because few nutrients enter.

"The sea here is so miserly that it takes one million years for a meter of marine “snow”—corpses, poo and dust—to accumulate on the bottom. The tale of all that time can total as little as 10 centimeters. It is the least productive patch of water on the planet.

***

"...the tubes contained up to 100 million years of Earth history. What the team wanted to know was how long and in what state microbes trapped in this milieu could survive in an almost-completely raided oceanic refrigerator.

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"Their results, published in Nature Communications in July, revealed that the sediments contained bacterial cells, which they expected (not many, though: just 100 to 3,000 per cubic centimeter). But when given food, most of them quickly revived, which the scientists did not expect.

"The microbes got straight to work doing what bacteria do, and within 68 days of incubation had increased their numbers up to 10,000-fold. They doubled about every five days (E. coli bacteria in the lab double in around 20 minutes). Their progeny contained specially labeled isotopes of carbon and nitrogen that made the scientists sure that the microbes were eating what they had been offered.

"It’s worth pausing to consider the meaning of these results. In this experiment, cells awoke and multiplied that settled to the bottom when pterosaurs and plesiosaurs drifted overhead. Four geologic periods had ground by, but these microbes, protected from radiation and cosmic rays by a thick coat of ocean and sediment, quietly persisted. And now, when offered a bite, they awoke and carried on as if nothing unusual had happened.

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"Somewhat surprisingly, the majority of the cells were, like us, forms that breathe oxygen. In fact, the sediment they were pulled from is full of oxygen. Clearly, lack of “air” is not the problem for the life in gyre sediments. It’s the lack of food.

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"Putting it all together—the tight quarters, the lack of spores and the rapid reanimation—these scientists think it’s likely that the majority of the bacteria in this impoverished sediment have been alive but idling these 100 million years.

"A few years ago, I wrote about bacteria that may have been resurrected from coal from the Paleozoic. Now we have reports of bacteria from the Cretaceous seafloor sediment waking apparently nonplussed. Back then I speculated that under certain highly constrained but possibly abundant conditions, bacteria may be effectively immortal. Now it seems even more likely we may be sitting atop a planet that’s full of living fossils that are literally that—both fossils and alive."

Comment: two major points. Some forms are designed to be able to live forever. The need to survive does not drive evolution. That 99% are gone is of no import. And here must be adequate food supply for life to thrive.