NASA's NextGen Astronauts - Bacteria With the Ability to Survive Radiation & Rapidly Repair Its Own DNA

A plot for the next Ridley Scott space thriller? The eye of the next generation HAL 9000? Guess again. NASA is experimenting was an extremeophile bacteria that could survive on another planet. In an Earth lab, Deinococcus radiodurans (D. rad) survive extreme levels of radiation, extreme temperatures, dehydration, and exposure to toxic chemicals.

Amazingly, they even have the ability to repair their own DNA, usually with 48 hours. D. rad is capable of withstanding an instantaneous dose of up to 5,000 Gy of ionizing radiation with no loss of viability, and an instantaneous dose of up to 15,000 Gy with 37% viability.  The symbol Gy for a “gray,” is the unit of absorbed radiation dose due to ionizing radiation such as X-rays).

A dose of 5,000 Gy is estimated to introduce several hundred complete breaks into the organism’s DNA. By comparison, 10 Gy can kill a human, over 4000 to kill the radiation-resistant tardigrade, and 60 Gy will kill E. coli. It accomplishes its resistance to radiation by having multiple copies of its genome and rapid DNA repair mechanisms. It usually repairs breaks in its chromosomes within 12-24 hours through a 2-step process.

Known as an extremophile, bacteria such as D. rad are of interest to NASA partly because they might be adaptable to help human astronauts survive on other worlds. A recent map of D. rad’s DNA might allow biologists to augment their survival skills with the ability to produce medicine, clean water, and oxygen. Already they have been genetically engineered to help clean up spills of toxic mercury. Likely one of the oldest surviving life forms, D. rad was discovered by accident in the 1950s when scientists investigating food preservation techniques could not easily kill it.

A team of Russian and American scientists proposed that evolution of the microorganism could have taken place on the Martian surface until it was delivered to Earth on a meteorite. However, apart from its resistance to radiation, D. rad is genetically and biochemically similar to other terrestrial life forms, arguing against an extraterrestrial origin.

Casey Kazan

Source: NASA/Apod

Image credit:
Credit: Michael Daly (Uniformed Services University of the Health Sciences), DOE