(ORDO NEWS) — Scientists have discovered tiny bubbles in 830-million-year-old rock salt crystals that contain traces of organic matter – and possibly the oldest bacteria and algae. Can salt really preserve living things for hundreds of millions of years? Or are we wishful thinking?
Salt crystals growing at the bottom of drying water bodies can capture microscopic drops of the surrounding water – geologists call them primary inclusions – and with them are able to “preserve” in their bowels any solids that were, say, in the water around them. The composition of such inclusions can include both mineral substances and organic, and sometimes whole organisms.
So, in 2000, a controversial study was published that described a bacterium of the genus Virgibacillus extracted from a salt crystal , which had been dormant for the past 250 million years. The article was met with a flurry of criticism from geologists, chemists and geneticists.
And although it was not possible to completely exclude the preservation of the microorganism in a “preserved” state, even the discoverer of “ Virgibacillus species 2-9-3” himself could not say how the bacteria managed to exist for so long.
Now a new article has been published in the journal Geology , which describes microorganisms that are more than three times older than the former “long-liver”.
Australian scientists studied salt samples recovered from a depth of one and a half kilometers from the Browne Formation in Western Australia: deposits of this formation formed about 800 million years ago, in the Neoproterozoic , at the bottom of a shallow lagoon or drying lake.
Having studied thin sections of salt crystals under a light microscope, the researchers saw primary inclusions in them – tiny bubbles filled with liquid.
With the help of non-invasive research methods (photography in ordinary and UV-visible light), it was possible to fix the presence of prokaryotic and eukaryote-like organisms and organic compounds in the vesicles.
Prokaryotic microorganisms with a diameter of about a micrometer can be archaea or bacteria (or spores of bacteria), while eukaryote-like microorganisms – up to five micrometers in diameter – look like unicellular algae.
Most intriguingly, the authors of the study suggest the possibility that these microorganisms, whose age is almost a billion years old, may still be alive.
This is evidenced by the low degree of degradation of organic matter and the preservation of the cell shape.
If this is true, then the new study is of great importance for the search for traces of extraterrestrial life: it is known that the surface of the Red Planet was once covered with vast salt lakes, and halite crystals similar to those from the Brown Formation could well have formed at their bottom.
In this case, having studied Martian samples of rock salt, we will be able to detect dormant microorganisms in their inclusions and put an end to the question of whether extraterrestrial life exists.
In conclusion, I would like to say that the conclusions of Australian scientists should be taken with a great deal of caution: although the statements sound loud, in fact they may be premature, if not false at all.
For a full-fledged conclusion about the age of “Neoproterozoic microorganisms”, it is necessary at least to extract samples of microorganisms from salt inclusions and conduct a more thorough study involving geneticists and microbiologists.
So far, more or less unequivocally, one can speak about the presence of organic substances in rock salt inclusions, which, of course, is curious, but can hardly be called a sensation.
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