Microbial Record Holders

Oldest Living Microbes

In the fairy tale, Sleeping Beauty went to sleep for 100 years in a castle protected by giant thorns and then was revived by the kiss of a prince. In 2000, scientists told a microbial version of this fairy tale, announcing that they had revived bacteria that had lain in suspended animation for 250 million years, encased in salt crystals deep in the Earth.

(Of course, the scientists did it by putting the bacteria in special nutrients, not with a kiss! See this ancient_sporenews report for the details.) If these scientists' claims are proved true, these microbes will take the prize as the oldest living things on Earth by far.

250 million years old—Wow, now that’s old! The first dinosaurs were just starting to appear on Earth at that time. It would be another 45 million years before Tyrannosaurus rex roared its first roar. The scientists believe that the bacteria got trapped in the salt crystals, which were buried 1,850 feet down under what’s now Carlsbad, New Mexico, in the southwestern United States.

How could the bugs possibly survive all that time, century after century, millennium after millennium, and suddenly wake up all perky when put into a nutrient-rich petri dish? The answer could be spores. The bacteria appear to be similar to modern day soil bacteria that form protective spores when things get tough. Spores are kind of like plant seeds—a tough protective shell insulates and protects the genes and basic cell parts, which are in an inactive state (that means they aren’t doing anything but just sitting there). Spores are much, much tougher than plant seeds, however. Spores can even survive blasts of radiation as well as years of going with no water or nutrients. If you want to know more about spores, visit this page on our site: How Bacteria Form Spores.

Scientists know that modern-day soil bacteria spores can revive after many years. But 250 million years??? Some scientists think that these microbial sleeping beauties are a fairy tale themselves. These scientists say that there needs to be more proof that the bacteria found in the salt crystals didn’t seep into the salt beds at a more recent time. Or perhaps the bacteria found in the crystals were microbes that contaminated the lab or the instruments used to drill into the salt. (See this news article for more details on why some scientists doubt the ancient age of these microbes.)

The scientists who did the experiments say that they took extra care to make sure there was no chance for contamination. Even so, their work will have to be repeated by other teams of scientists if everyone is to accept the idea that 250 million-year-old bacteria spores can be revived. This is what the scientific process is all about: piling up evidence upon evidence until you have eliminated all possible explanations but one.

amber spore

However, earlier work on raising ancient microbes from their dormant sleep makes it a little easier to believe these latest claim—and the latest work makes it easier to believe the earlier findings. In 1995, scientist Raúl Cano and his coworkers announced that they’d revived 30-million-year-old bacteria that had lived in the gut of an ancient bee. The bee and its microbial guests got trapped and preserved in a drop of tree sap that became amber. To learn more about this discovery and about Dr. Cano, read his profile in the Careers section of MicrobeWorld. Cano’s team also ran into skepticism from others when they announced their findings. It’s tough to prove something this amazing beyond any shadow of a doubt. But if more examples of revived ancient microbes occur, it may well become accepted by everyone that prehistoric microbes are now dwelling happily in petri dishes in scientists’ labs.

Final note: Is there any danger in reviving ancient bacterial spores? Not likely. There’s no more risk that scientists will grow dangerous ancient microbes than they'll grow dangerous modern-day ones from samples they are taking from all over the world. In fact, scientists are finding and growing lots of previously unknown modern microbes all the time from all kinds of environments and so far no one has grown up any deadly microbes (at least not to my or my colleagues’ knowledge). You’ve got lots more to worry about from the microbes floating in the air from your pal’s sneeze than any revived ancient microbes. Also, scientists take great care in growing and storing these ancient microbes in secure lab environments so that they don’t ever come into contact with the outside world. But that’s because the scientists have to protect the ancient microbes from modern microbes or other things outside the lab, not the other way around.

 

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