The World's Most Indestructible Bacteria Can Survive Conditions That Would Kill A Human

The world is full of unfathomably resilient creatures, and many of them happen to be microscopic. It might seem unintuitive that many of the tiniest organisms in existence are some of the toughest to ever exist, but these miniscule creatures really are that hardy. The tardigrade, for instance, is considered nature's most indestructible organism despite the fact that, under a microscope, it looks like fragile moving glass.

But when it comes to organisms that are insanely hard to kill, Deinococcus radiodurans might just be the king — at least in one very specific way. This poly-extremophilic bacterium is particularly noteworthy for its resistance to high levels of radiation. How much radiation can D. radiodurans withstand? Well, the bacterium is known as the most radioresistant organism ever known and is capable of holding up even when exposed to 1.5 million rads of gamma radiation, which is around 3,000 times what would kill a human in just a few hours.

But D. radiodurans can also deal with multiple extreme environments and situations, from ultraviolet radiation to oxidation and desiccation,making it a truly hardy little bacterium which might even be able to outdo the tardigrade in certain situations.

Bacteria are tiny, single-celled living organisms and there are several types known for being highly resilient — Escherichia coli (E. coli) being one well-known example. For the most part, scientists are particularly concerned about antibiotic-resistant bacteria, which pose a huge threat to our collective health. But D. radiodurans — dubbed "Conan the Bacterium" by some scientists — is resilient in an entirely different way.

Back in the 1950s, American scientists discovered this tiny extremophile in canned meat. As detailed in the 1956 paper "Studies on a radio-resistant micrococcus. I, Isolation, morphology, cultural characteristics, and resistance to gamma radiation," after exposing canned meat to high levels of ionizing radiation, the researchers were surprised to find a microorganism inside which had survived. D. radiodurans has since fascinated experts who have been trying for decades to understand the key to this bacteria's unique hardiness, particularly in terms of its resistance to ionizing radiation (IR).

Thus far, research has shown the radioresistance of the bacteria dwarfs any other known organism. It has 30 times the radioresistance of E. coli and more than 1,000 times more than us humans. Experts have also identified multiple aspects of D. radiodurans that aid in its resilience to IR, from its cell wall and genome composition to its highly efficient ability to repair DNA and its antioxidant defense system. What's more, scientists are still learning about the mechanisms that allow the bacteria to remain so tough, revealing facts about the bacterium that could have a major impact on humanity's future.

Despite the decades of work that has gone into understanding D. radiodurans and its unique ability to withstand extreme conditions, there's still a lot more work to do. Thankfully, recent research has managed to shed even more light on the topic. In a 2024 study published in the journal Proceedings of the National Academy of Sciences researchers revealed one big piece of the puzzle that contributes to D. radiodurans' remarkable resilience to radiation. The team identified three components of the bacteria's cell — manganese ions, phosphate, and peptides — which together form an antioxidant capable of withstanding radiation to a degree that was previously unknown. Rather than each individual component enhancing the bacteria's resistance to radiation, then, the three components themselves actually form something new, thereby representing the very definition of the term "greater than the sum of its parts."

In the future, scientists hope to harness their knowledge of D. radiodurans' resistance to radiation in order to develop more effective radiation protection and medicine for humans. It could lead to the creation of synthetic antioxidants, which would have big implications for things such as space exploration, where astronauts might have to endure extreme levels of radiation. It's thought that D. radiodurans could withstand the levels of radiation on Mars, for instance, and considering humanity's ongoing fascination with the red planet and ambitions to send astronauts in the near future, what we learn from the bacterium could prove to be invaluable.