Theoretical origin of life; aged subterranean extremophiles (Introduction)

by David Turell , Friday, January 25, 2019, 00:59 (1910 days ago) @ dhw

They can exist without light, without water, without oxygen, and may metabolize carbo

https://blogs.scientificamerican.com/artful-amoeba/inside-earth-microbes-approach-immor...

"Last month, the Deep Carbon Observatory announced an astounding fact: the mass of the microbes living beneath Earth’s surface amounts to 15 to 23 billion tons of carbon, a sum some 245 to 385 times greater than the carbon mass of all humans. That’s amazing. It wasn’t so long ago we weren’t even sure life at depth was possible.

"But buried in the press release was a detail I found much more surprising and interesting than the mass of subterranean life: its age.

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"Back in the late 1920s, a scientist named Charles Lipman, a professor at the University of California, Berkeley, began to suspect there were bacteria in rocks. Not fossil bacteria. Alive bacteria.

"Lipman did not believe that the bacteria he coaxed from coal were alive in the sense that the bacteria in your gut are alive. Rather, he believed that during the process of forming coal, the bacteria had dried up and entered suspended animation.

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“'It is my view that here and there scattered through the masses of the coal measures an occasional spore or some similarly resistant resting stage of a microorganism has survived the vicissitudes of time and circumstance and retained its living character, its power to develop into a vegetative form, and its power to multiply when conditions are rendered propitious for it.”

"This dessicated condition we now call anhydrobiosis, and it is in such a state that organisms like water bears can withstand the vacuum of space and bombardment with radiation.

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"A 2017 paper in the Proceedings of the National Academy of Science found low densities of bacteria (although “low” is still 50-2,000 cells per cubic centimeter) in 5 to 30 million-year-old coal and shale beds located two kilometers beneath the floor of the Pacific Ocean off the coast of Japan.

"They were still actively, if extremely slowly, living. Their generation times ranged from months to over 100 years. But this estimate was likely low, the authors conceded. The generation time of E. coli in the lab: 15 to 20 minutes.

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'Evidence is also accumulating that such nutrient-deprived, superannuated bacteria are not “microbial zombies”. On the contrary, numerous studies have found that when deep subsurface microbes are placed in more moderate environments, they quickly revive.

"Taken together, these findings aren’t as ludicrous as they may seem when you also consider that microbes buried deep beneath Earth’s surface are protected from cosmic radiation – a frequent killer of the preternaturally aged – by thick overburdens of water, sediment, and/or rock (Muons, the form in which cosmic radiation reaches Earth’s surface, can only penetrate tens of meters into rock). Such radiation steadily mutates the DNA of organisms living on Earth’s surface.

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"To sum up, Earth’s crust appears to be simply lousy with idling, ancient bacteria parked in power-save mode, ready at nearly a moment’s notice to throw the gearshift into drive. But what a life! Eons spent entombed in a dark, airless, silent matrix, barely eating, barely breathing, barely moving, barely living. But not dead. Not dead.

"If Charles Lipman was right, there are also bacterial cells inside our planet that began life 50 million years before dinosaurs evolved that could begin dividing again tomorrow. That … is breathtaking."

Comment: Wow!! What this means is that the process of life is exceedingly tough and can last though any type of trial. If they date back to before dinosaurs (250 myo) they were alive deep in the Earth at 300 myo!