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Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

sciencemag.org

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Re: Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

#51

Post by ballenf »

ryanschneider wrote: post #28
esquire_900 wrote: post #2

> we found that up to 99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat > But the real secret of their remarkable survival lies in their metabolic rate. It is just slow enough for them to survive for such long periods. That would imply their metabolic rate to be practically zero, 101 million years is such a long time that even the tiniest amount of activity wou…

> were ready to eat Am I the only one who pictured the lab workers munching on 100M year old microbe colonies?

And you just made me picture a store bought "ready-to-eat" meal as a terrifying and hungry creature waiting for me to wake it up.

Re: Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

#53

Post by wombatmobile »

kitd wrote: post #3
esquire_900 wrote: post #2

> we found that up to 99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat > But the real secret of their remarkable survival lies in their metabolic rate. It is just slow enough for them to survive for such long periods. That would imply their metabolic rate to be practically zero, 101 million years is such a long time that even the tiniest amount of activity wou…

I wondered that too. "Die" implies not just metabolic rate going to zero, but also cells "disassembling" too ("decomposing" feels a bit large-scale in this context). It did say that there were microscopic amounts of oxygen in the sediment. Presumably, that was enough to maintain a minimally-small MR.

> The presence of dissolved O2, nitrate (NO3−), phosphate (PO4−), and dissolved inorganic carbon (DIC) throughout the sedimentary sequence from the seafloor to the volcanic basement indicates that cell abundance and activity are not limited by availability of electron acceptors or dissolved major inorganic nutrients. From the Redfield stoichiometry of net dissolved O2 reduction to net nitrate production in the sediment, the microbial cells have been inferred to consume oxygen coupled to oxidation of marine organic matter at extremely slow rates.

-- D’Hondt, S. et al. Presence of oxygen and aerobic communities from sea floor to basement in deep-sea sediments. Nature Geosci. 8, 299–304 (2015).

Re: Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

#54

Post by wombatmobile »

HPsquared wrote: post #23

Are the microbes themselves that old, or simply made of old material? Edit: quoting the article, it doesn't say the microbes themselves are 100M years old, only that they're in sediment which is that old. Big difference! "99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat"

From the paper

> Very low permeability (1.1–2.0 × 10−17 m2 for IODP Site U1365 4H-3 [26.6 meters below seafloor (mbsf)] and 8.9 × 10−18 m2 for IODP Site U1370 [37.5 mbsf], respectively), very low estimated pore size of the abyssal clay (~0.02 microns, calculated using above permeability data according to the equation shown in Tanikawa et al.), and thick porcellanite layers above the oldest sampled horizons appear to preclude cell migration into the sampled sediment. Consequently, the sampled communities have likely been trapped in the sediment since shortly after its deposition.

Re: Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

#57

Post by _0w8t »

Ovah wrote: post #40
esquire_900 wrote: post #2

> we found that up to 99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat > But the real secret of their remarkable survival lies in their metabolic rate. It is just slow enough for them to survive for such long periods. That would imply their metabolic rate to be practically zero, 101 million years is such a long time that even the tiniest amount of activity wou…

And DNA appears to have a half-life of 521 years. 101 million years is 194 817 half-lifes. Assuming the research is sound I wonder how the bacteria get around that limit.

The stability of any complex organic molecule depends very strongly on the temperature, acidity, presence of other components etc. Without reference to the precise conditions the number is meaningless.

Re: Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

#58

Post by excannuck »

Ovah wrote: post #40
esquire_900 wrote: post #2

> we found that up to 99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat > But the real secret of their remarkable survival lies in their metabolic rate. It is just slow enough for them to survive for such long periods. That would imply their metabolic rate to be practically zero, 101 million years is such a long time that even the tiniest amount of activity wou…

And DNA appears to have a half-life of 521 years. 101 million years is 194 817 half-lifes. Assuming the research is sound I wonder how the bacteria get around that limit.

I'd expect DNA's half life would depend on the environmental conditions. The conditions on the surface of the earth and at the bottom of the ocean are vastly different.

DNA stabilizing:

Much lower T (below 0C) Practically no radiation (an ocean above you blocking it all)

DNA de-stabilizing: Corrosive chemicals spewing from a nearby volcano (but only if one is near you!) Radiation from said volcano and rocks (but they'd have to be closer still, due to shielding from the water)

So unless the 500 year half life is the "self-damaging" rate, I'd expect DNA at the bottom to last much longer.

Re: Living microbes, possibly 100M years old, pulled from beneath the sea (2020)

#59

Post by patall »

Ovah wrote: post #40
esquire_900 wrote: post #2

> we found that up to 99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat > But the real secret of their remarkable survival lies in their metabolic rate. It is just slow enough for them to survive for such long periods. That would imply their metabolic rate to be practically zero, 101 million years is such a long time that even the tiniest amount of activity wou…

And DNA appears to have a half-life of 521 years. 101 million years is 194 817 half-lifes. Assuming the research is sound I wonder how the bacteria get around that limit.

No, DNA does not have a half-life of 521 years. To give the correct citation: ''' By analysing mitochondrial DNA (mtDNA) from 158 radiocarbon-dated bones of the extinct New Zealand moa, we confirm empirically a long-hypothesized exponential decay relationship. The average DNA half-life within this geographically constrained fossil assemblage was estimated to be 521 years for a 242 bp mtDNA sequence, corresponding to a per nucleotide fragmentation rate (k) of 5.50 × 10–6 per year. With an effective burial temperature of 13.1°C, the rate is almost 400 times slower than predicted from published kinetic data of in vitro DNA depurination at pH 5. ''' from https://royalsocietypublishing.org/doi/10.1098/rspb.2012.174...

Or in laymens words: the half-life of a DNA molecule per nucleotide depends on the environment and is in the order of magnitude around 1 million years. Else, we would not have any ancient genomes by now.

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