
Scientists Waited Two and a Half Years to See Whether Bacteria Can Eat Rock - headalgorithm
https://blogs.scientificamerican.com/artful-amoeba/scientists-waited-two-and-a-half-years-to-see-whether-bacteria-can-eat-rock/
======
mattkrause
Original paper: Napieralski, S., Buss H., Brantley S., Lee S., Xu, H. and
Roden, E (2020). "Microbial chemolithotrophy mediates oxidative weathering of
granitic bedrock." _PNAS_ 116 (52) 26394-26401; DOI: 10.1073/pnas.1909970117.

PDF:
[https://www.pnas.org/content/pnas/116/52/26394.full.pdf?casa...](https://www.pnas.org/content/pnas/116/52/26394.full.pdf?casa_token=11TLH4jWjpwAAAAA:mkryEkwF8HYDUjnzftrI70FPccyiSh8dtQuqiYW9wpjvf1Zx4A2niSNiBORXJAvOd8GGwuMJoZEneJYI)
(works, even though it seems like it shouldn't...)

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lidHanteyk
This is exciting experimental evidence for the concept of lithotrophy [0];
while we knew about the mechanisms of action for a while, and have previously
found rock-eating microbes within otherwise-unliving rocks, this experiment
shows us that these microbes are part of the circle of life.

[0]
[https://en.wikipedia.org/wiki/Lithotroph](https://en.wikipedia.org/wiki/Lithotroph)

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fulafel
Bacteria are also used in mining to refine the ore:
[https://en.wikipedia.org/wiki/Bioleaching](https://en.wikipedia.org/wiki/Bioleaching)

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yonrg
Only 2.5 yrs? This reminds of
[https://en.wikipedia.org/wiki/Pitch_drop_experiment](https://en.wikipedia.org/wiki/Pitch_drop_experiment)

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DonHopkins
Stop treating the Earth like dirt!

More muck-racking journalism from Scientific American:

Would You Like a Side of Dirt with That?

[https://www.scientificamerican.com/article/would-you-like-
si...](https://www.scientificamerican.com/article/would-you-like-side-dirt-
eating-soil/)

Pay Dirt: Martian Soil Fit for Earthly Life

[https://www.scientificamerican.com/article/martian-soil-
fit-...](https://www.scientificamerican.com/article/martian-soil-fit-for-
earthly-life/)

Eating Dirt: The Benefits of Being (Relatively) Filthy

[https://blogs.scientificamerican.com/food-matters/eating-
dir...](https://blogs.scientificamerican.com/food-matters/eating-dirt-the-
benefits-of-being-relatively-filthy/)

Dirt Doesn’t Smell like Dirt

[https://blogs.scientificamerican.com/artful-amoeba/dirt-
does...](https://blogs.scientificamerican.com/artful-amoeba/dirt-doesnt-smell-
like-dirt/)

Why Researchers Need Better Space Dirt

[https://www.scientificamerican.com/article/why-
researchers-n...](https://www.scientificamerican.com/article/why-researchers-
need-better-space-dirt/)

Secrets of Life in the Soil

[https://www.scientificamerican.com/article/secrets-of-
life-i...](https://www.scientificamerican.com/article/secrets-of-life-in-the-
soil/)

How Dirt Cleans Water

[https://www.scientificamerican.com/article/how-dirt-
cleans-w...](https://www.scientificamerican.com/article/how-dirt-cleans-
water/)

Dirt Poor: Have Fruits and Vegetables Become Less Nutritious?

[https://www.scientificamerican.com/article/soil-depletion-
an...](https://www.scientificamerican.com/article/soil-depletion-and-
nutrition-loss/)

How Dirt Can Clean the Air

[https://www.scientificamerican.com/article/how-dirt-can-
clea...](https://www.scientificamerican.com/article/how-dirt-can-clean-the-
air/)

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owenversteeg
Jesus, this is a bad article. It's filled with several very bad attempts at
humor and buries the lede but my main problem is that it's just wrong.

"there is an enduring mystery to dirt: where does it come from?", "Mystery of
dirt’s origins is a thorny experimental problem"

Why would they try to pretend nobody knows where soil comes from!? Did they
not even bother to Google the word "soil"? "Soil formation" is the third
heading on Wikipedia. There's an entire field dedicated to soil formation:
pedogenesis! Soil science isn't some new start-up field where everything's
unknown - soil scientists can give you a pretty damned good estimate of not
only where soil comes from but how many nutrients it will have over time, what
microbes are in it, what will happen to the soil over time, etc etc.

Unfortunately this kind of thing seems to be par for the course for SciAm. A
writer picks out some random new research and writes about it as if it's
groundbreaking. Unfortunately, 99.5% of research isn't the discovery of DNA,
it's "we tested if bacteria A has more xyz than bacteria B and the difference
was not statistically significant."

I'm reminded of [https://xkcd.com/683/](https://xkcd.com/683/)

~~~
brudgers
Logically, all xkcd references in comments resolve to
[https://xkcd.com/386/](https://xkcd.com/386/) including this one.

~~~
neonate
Nice. Did you just come up with that?

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celloductor
TLDR- yes it can.

"The minerals incubated with microbes appeared ragged or pitted — as if they
had been dipped in acid, not bacteria — after their 864-day incubation. The
sterile control minerals, by contrast, retained sharp, smooth edges."

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glofish
misleading title, they did not wait, wait means something completely different

they ground the rock up, placed it in a tube, put it in a drawer, then took it
out two years later and performed some measurements

the minerals turned out to be less jagged than sterile minerals kept for the
same amount of time. The scientists concluded that the bacteria ate the rock
by stripping electrons.

Now a possible alternative explanation (not explored by the journalist) is
that the bacteria lived off the remaining organic materials in the rock and
the byproduct of their life were substances that dulled the crystals.

~~~
dmurray
The alternative explanation is that they mined the rock for food? That's just
as interesting.

~~~
mattkrause
I think that's actually the result!

I read @glofish's proposal as suggesting that bacterial excretions(?)
indiscriminately dissolve the rock.

The paper (linked above) does try to address this in a few ways. Iron, the
putative energy source, is specifically concentrated on the surface of the
inoculated samples--but other metals aren't. The bacteria are also mostly
found on the mineral edges. They discuss this near Figure 5/6 and in the
supplement.

