Superbug Survives Radiation

Biological Strategy

Bacteria

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Protect From Nuclear Radiation

Nuclear radiation is a threat that some living systems can survive. Most survival strategies help living systems survive other kinds of extreme threats, although in situations where there has been human-caused exposure to nuclear radiation, some quickly reproducing organisms (such as bacteria) might develop new strategies. The tardigrade (also called a water bear) survives extreme conditions by undergoing a suspended metabolic state called cryptobiosis. Going into this state helps it survive nuclear radiation, dehydration, and low temperatures.

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Bacteria

Domain Bacteria (“small staff”): L. acidophilus, Staphylococcus

From inside of our own bodies to the deepest parts of the ocean, bacteria have adapted to almost every possible environment. All bacteria are unicellular, microscopic, and lack a membrane-bound nucleus and organelles, and come in three basic shapes: spherical (cocci), rod (bacilli), and spiral (spirilla). Some strains can be deadly, like Staphylococcus aureus (MRSA) while others, like Lactobacillus acidophilus, found in our intestinal microbiome, keep us healthy. Cyanobacteria, also known as blue green algae, caused the Great Oxidation Event 2.4 billion years ago, producing Earth’s first oxygenated atmosphere.

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The genome of Deinococcus radiodurans can survive extreme radiation because it prevents oxidative damage to its repair proteins via manganese ions.

“Deinococcus radiodurans can survive doses of ionising radiation thousands of times stronger than would kill a human. So how does it do it?

“Radiation shatters DNA into fragments, and it has long been thought that this is what makes it dangerous, explains Michael Daly of Uniformed Services University of the Health Sciences in Bethesda, Maryland.

“Not so, Daly says: instead it is damage that is the killer. ‘The ability of cells to survive radiation is highly dependent on the amount of protein damage caused during irradiation.’

“By exposing Deinococcus and other resistant bacteria to radiation, Daly’s team found that the resilience of a cell’s repair proteins is linked to the number of manganese ions in the cell. Manganese prevents oxidative damage to repair proteins and allows them to swing into action after radiation has damaged DNA (PLoS Biology, 10.1371/journal.pbio.0050092).

“In effect, this means that it doesn’t matter if your DNA is broken up, as long as you can stitch it back together with repair proteins. The implication is that if you keep your repair systems intact, then – like Deinococcus – you’ll be able to survive high doses of radiation.

“Daly speculates that it may be possible to deliver Deinococcus repair proteins into animal cells and so increase radiation resistance. This could be useful in space travel, where radiation sickness is a potential problem on long interplanetary journeys.” (New Scientist 2007:21)

Last Updated August 18, 2016

References

Journal article

Beetle's beauty lies in imperfection

New Scientist,

Journal article

Tough bug reveals key to radiation resistance

New Scientist,

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