This life that had been sleeping for 100 million years was awakened by a man-made accident.

A freshwater lake that was originally 3 meters deep turned into a 60-meter-deep saltwater lake after an accident, and a life that had been sleeping for 100 million years awakened.

Lake Peignur, located on Jefferson Island in Louisiana, is a beautiful freshwater lake with rich resources. At the bottom of the lake is a salt mine where Diamond Crystal Salt mines rock salt. On the surface of the lake, Texaco plans to explore for oil.

But everything changed on November 21, 1980. On that day, a Texaco rig miscalculated where to start drilling, and the drill bit accidentally penetrated the top of the third layer of the Pinel Lake Salt Mine.

Image source: Unsplash

Artificial vortex

A terrible thing happened. A large amount of lake water poured into the salt mine at the bottom of the lake, forming a huge artificial whirlpool on the lake surface. The seven crew members who originally planned to save the drilling platform found that the platform had begun to tilt, so they had to choose to escape. They watched the 46-meter-high derrick disappear in the lake, which was originally only 3 meters deep. At the same time, the lake water also flooded the mine 430 meters underground. The salt mine workers evacuated to the highest level of the mine in an emergency, but the lake water soon rose to waist-deep.

The salt pillars that were originally used to support the mine at the bottom of the lake gradually dissolved after the lake water poured in, and the salt mine tunnel collapsed. The hole at the bottom of the lake became larger and larger, and more lake water poured in. The once peaceful Lake Pinel now seemed to have turned into a huge black hole, swallowing everything around it. 11 barges, a tugboat, parking lots, countless trees, 35 hectares of lakeside land, and part of a building were all sucked in. Witnesses said, "It's like watching a duckling in a bathtub fall into the sewer."

In the past, the water of Lake Pinel was fed by the Vermilion-Teche Basin, and then flowed from Lake Pinel through the Delcambre Canal into Vermillion Bay and then into the Gulf of Mexico. At this time, under the influence of the vortex, a large amount of fresh water from the source poured in. On the other side, the Delcambre Canal also began to fill the lake, and the salt water from the Gulf of Mexico flowed upstream and entered the almost empty lakebed, resulting in a 50-meter-high temporary waterfall here, which is also the largest waterfall ever recorded in Louisiana.

At the same time, for the salt mine at the bottom of the lake, the massive influx of lake water means the rapid discharge of air in the mine. This compressed air gushes out from the main mine shaft along with the influx of lake water, forming a mud fountain as high as 122 meters, erupting intermittently.

The Delcambre Canal forms a waterfall by backflowing. Image credit: YouTube via @ankerssm

It was not until a few days after the accident that the water pressure in Lake Pinel and the salt mine reached equilibrium. Nine of the 11 barges that were originally sucked into the lake bottom by the whirlpool were ejected as if by a miracle and floated on the water again. At the same time, due to the large amount of salt water backflow, the original 3-meter-deep freshwater lake became a 60-meter-deep saltwater lake , and Lake Pinel became the deepest lake in Louisiana.

A life that has been sleeping for 100 million years

In 1985, Russell H. Vreeland, then an assistant professor of biology at the University of New Orleans in Louisiana, was granted access to some abandoned salt mines at the bottom of Lake Pinnell and collected some water samples. Vreeland also collected water samples from two brine companies in Oklahoma, intending to analyze the microbial composition of these samples. After isolation and cultivation, Vreeland discovered several extremely halophilic archaea that can survive in at least 20% salt water, with the best survival salinity being 25% to 30%.

It is not uncommon to find euryhaline bacteria (bacteria that can survive in waters with wide variations in salinity) in underground saltwater, as they may enter the ground with rainwater and gradually adapt to the increasing salinity as they travel through the ground. However, extreme halophilic archaea can only survive in high-salinity environments and are therefore extremely rare in underground saltwater. Where do they come from?

Mud fountain in the mine next to Lake Pinner. Image credit: YouTube via @ankerssm

Freeland first considered that these archaea may have originally lived in the water of Lake Pinel and rainwater, and then entered the mines and strata. However, the experimental results showed that these extremely halophilic microorganisms could not survive in fresh water or water with a salt content of less than 15%, and would directly lyse. Moreover, Freeland only detected these halophilic microorganisms in samples with higher salt concentrations.

Take the two samples from Oklahoma as an example. They come from different strata in the same basin, with sampling points less than 400 meters apart, and the water source comes from rainwater that infiltrates the strata. The only difference between the two samples is the salt concentration: one is 25% and the other is 8%. The results show that there are a large number of halophilic and salt-tolerant microorganisms in the high-salt concentration samples, while there are only salt-tolerant microorganisms in the low-salt concentration samples. The salt content of Lake Pinnell is less than 1%, so it is impossible to be the source of these halophilic microorganisms.

Considering that the sampling points of these water samples are directly connected to the outside world, Freeland also explored whether these extreme halophilic archaea could enter from the surface through pipelines or mines. However, researchers have never detected such extreme halophilic microorganisms in any hypersaline lake . Moreover, there is abundant rainfall near Lake Pinel, and the geological and topographic conditions are not suitable for the formation of a hypersaline environment. Therefore, there does not seem to be a source of such microorganisms on the nearby surface.
In this case, is it possible that these archaea were originally ordinary bacteria, and later evolved the special ability of extreme salt love? From the perspective of molecular biology, archaea and bacteria are very different, and it is difficult for bacteria to evolve into archaea through a series of mutations. It was only 5 years from the injection of lake water to the sampling in Freeland. It is extremely unlikely that such a significant evolution occurred in such a short period of time. If this is true, then this mutation rate is far higher than any species known to scientists.

Rock salt crystals from the Permian period. Image source: original paper

After ruling out these three possibilities, Freeland believes that the only remaining and reasonable explanation is that these archaea originally existed in the salt mine. They may have been locked in the crystals when the salt crystals were formed, or they may have been trapped in the water enclosed by the crystals in some way, and then gradually awakened as the crystals dissolved after the salt mine accident caused lake water to flood in or rainwater to seep into the ground.

If this hypothesis is true, it means that these archaea were already present when the halite crystals were formed. The salt at the bottom of Lake Pinnell comes from the Early Cretaceous period, 125 million to 121 million years ago, and the strata sampled from the two Oklahoma Basin sites are 100 million and 250 million years old, respectively. Therefore, these extremely halophilic archaea are likely to have survived in this form for hundreds of millions of years.

After the publication of this paper, more and more studies have shown that microorganisms may survive in mineral crystals for a long time. In 2000, Professor Freeland isolated and cultured a new strain of Bacillus from fluid inclusions in the Permian strata about 250 million years ago; in 2022, some scientists discovered microorganisms (but not cultured) 830 million years old in the Neoproterozoic strata in central Australia; another study in 2022 showed that Deinococcus radiodurans, also known as "Conan the Bacterium", could also remain dormant for 280 million years under freeze-drying conditions 10 meters below the surface.

The cover of the current issue of Astrobiology, which published the research on radiation-resistant Deinococcus. Image source: Astrobiology

Therefore, with the development of technology, under suitable conditions, perhaps more and more microorganisms that existed contemporaneously with the dinosaurs (or even earlier) will travel through time and space to meet us.

On October 31 this year, the "Jefferson Island 1" (JI-1) archaea isolated from the salt mine at the bottom of Lake Pinnell was classified by Professor Freeland as a new species of the genus Halorbrum and named "Halorubrum hochsteinianum" to commemorate the contributions made by scientist Lawrence Hochstein to extreme halophilic microorganisms.

References

[1]https://link.springer.com/article/10.1007/s00792-023-01320-4

[2]https://www.motherjones.com/environment/2013/08/sinkhole-swallowed-11-barges/

[3]https://en.wikipedia.org/wiki/Lake_Peigneur

[4]https://link.springer.com/chapter/10.1007/978-1-4615-3730-4_7

[5]https://www.economist.com/science-and-technology/2023/11/15/was-an-ancient-bacterium-awakened-by-an-industrial-accident

[6]https://www.nature.com/articles/35038060

[7]https://pubs.geoscienceworld.org/gsa/geology/article/50/8/918/613521/830-million-year-old-microorganisms-in-primary

[8]https://www.liebertpub.com/doi/10.1089/ast.2022.0065

[9]https://www.youtube.com/watch?v=p_iZr2-Coqc

[10]https://www.youtube.com/watch?v=cNo-gEPWVnM

Planning and production

Source: Global Science (ID: huanqiukexue)

Author: Huang Yujia

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Editor: Zhong Yanping