Underground microbes are almost immortal

Last month, the Deep Carbon Observatoryannounced a striking fact: the mass of microbes living below the surface of the Earth ranges from 15 to 23 billion tons of carbon, which is about 245-385 times the mass of carbon of all people. It's amazing. After all, not so long ago we did not even suspect that life was possible deep underground. However, behind all this, detail did not immediately become noticeable, which is more surprising and interesting than the mass of underground life: its age.

How to achieve immortality? Ask the microbes

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

He reflected on the fact that the bacteria in hislaboratories could be reanimated after 40 years spent in dry soil in sealed bottles. If they could survive four decades, was there any limit?

Coal was like a stone ripened for testing, grown from marsh mud. He began to crush pieces of coal to see if anything could sprout from the dust. It could.

After mixing the coal dust in sterile water, after two or three weeks he saw something similar to bacteria. Placing it in solutions with peptone, food of bacteria, he accelerated the resuscitation time to five hours.

What is curious, he discovered that the periodrehydration in liquid for two days was necessary for recovery. If the crushed coal was wetted, but after that it was immediately placed on food agar, similar to gelatin, in a Petri dish, nothing grew.

Of course, Lipman included precautionsto ensure that no pollutants cause growth. His draconian procedures for cleaning and sterilizing pre-crushed pieces included cleaning, soaking, baking, and squeezing pieces of coal for several hours or days before grinding. In fact, he found that heating the sample for several hours at 160 degrees Celsius never leads to the destruction of bacteria inside the coal. In any case, he even encouraged them. The longer they baked - up to an incredible 50 hours - the better they seemed to grow when the coal was subsequently broken. (If its results were genuine, they may not be so surprising, given the conditions under which coal is created).

Lipman did not believe that the bacteria hemade from coal, were alive in the same sense in which bacteria are alive in the intestines. Rather, he believed that during the process of coal formation the bacteria dried out and entered the freezing phase.

"... the microorganisms found in the coal are actuallyare survivors, imprisoned in coal during its formation from material that was originally probably very rich in microorganisms, because it looked like peat, ”he wrote in the Journal of Bacteriology. "I believe that occasional spores or some similar stable stage of rest of the microorganism scattered around the coal masses have experienced the vicissitudes of time and circumstances and have preserved a lively character, the ability to turn into a plant organism and the ability to reproduce in favorable conditions."

We now call this dried state anhydrobios, and in this state the slow-moving can withstand the vacuum of space and the bombardment of radiation.

Lipman's coal came from Wales and Pennsylvania, where part of it was mined at a depth of 900 meters. Pennsylvania coal inspired the name of a whole geological sub-period — the Pennsville.

He is at least 300 million years old.

It was 1931. His colleagues probably believed that Lipman was crazy. But here, in 2019, it seems increasingly likely that he was not crazy. The oldest living creatures in the world may not be bent spinous pines and not ancient aspens, but tiny microbes trapped in rocky rocks below the surface, the purpose of which is not to grow or reproduce, but simply to deceive death.

More and more recent worksdecade, show that bacteria living - many of them in a hydrated, active state - in sediments, in rocks, in pockets and fissures underground, are outdated data.

For example, in the early 2000s, scientistsfound that the rate at which the microbes in the aquifers and sediments breathed was significantly lower than that of the microbes on the surface. The biomass turnover rate — the time it takes to replace molecules in a cell — was measured from hundreds to thousands of years.

"We do not know whether microbes multiply in theseunderground environments with such a slow biomass turnover, ”wrote Frederick Cowell and Stephen D’Hondt in a 2013 Nature and Extent review of the Deep Biosphere,“ or live without division for millions and tens of millions of years.

In 2017, a work appeared in PNAS, in whichIt is shown that two kilometers under the bottom of the Pacific Ocean off the coast of Japan, in coal and shale deposits 5-30 million years old, a low density of bacteria was found (although the “low” still amounts to 50-2000 cells per cubic centimeter).

And they are still active, albeit very slowly,lived. The time of their generation varied from months to more than 100 years. But this estimate was probably understated. The generation time of E. coli in the laboratory is from 15 to 20 minutes.

In the study of microbes living in deep-seamarine sediments in the South Pacific, 2018, published in Geobiology, it was concluded that fitness in such sediments is not in growth, but in survival. The authors concluded that the only source of food for such microbes was that they were buried with them. The amount of carbon they use for maintenance and repair during the year was only 2% of their own carbon content in the cell.

“The fact that intact microbial cells are found in this ancient habitat has remarkable implications for the resistance of these organisms,” the authors write.

In their computer models that simulate a lotmillion years, after four million years, all cells stopped growing. They simply invested all the resources they could find to support the work of the old carcass.

How long can this game last with zeroprize money? Will microbes end up starving? Will they take a withered, frozen form, like the one that Lipman discovered? Or does it require special conditions?

Evidence is accumulating thatnutrient-deprived, elderly bacteria are not “microbial zombies”. On the contrary, numerous studies have shown that when deep underground microbes are placed in a more moderate environment, they quickly come to life.

In general, these findings do not seem ridiculous, given that the microbes buried deep beneath the earth's surface are protected from cosmic radiation — by thick layers of water, sediment, rocks. The muons that are present in cosmic radiation reaching the surface of the Earth can break through only a few tens of meters of rocks. Such radiation constantly irradiates the DNA of organisms living on the surface, leading to their mutation.

The hypotheses of panspermia that life has filledTraveling by hitchhiking inside asteroids to the universe always seemed something supernatural. But these findings, together with the recent realization that life could appear on Earth almost immediately, together with the formation of the planet, force us to reconsider this attitude. Although space is huge, life will find its way.

Summing up, we can say that the crustIt looks just lousy with idle, ancient bacteria, parked in power saving mode and ready to come to life at any moment. But what kind of life! Epochs spent in burial in a dark, airless, silent matrix, barely eating, barely breathing, barely moving, barely living. But not dead.

If Charles Lipman was right, on our planetthere are also bacterial cells that began life 50 million years before the advent of dinosaurs, which may begin to divide again tomorrow. It is breathtaking.

However, the price of practical immortality is to remain locked up in an underground prison.

Agree, it is not much different from the burial of people.

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