In 1956, Arthur W. Anderson discovered Deinococcus Radiodurans when isolating bacteria from a can of ground meat that had spoiled, despite it being sterilised with radiation by means to preserve the contents.
At 2 micrometres in diameter, Deinococcus Radiodurans can survive extreme radiation, and has been found thriving in many places -including the inside of nuclear reactor walls.
This unique microbe is a type of ancient bacteria, surviving with no clear genetic affinity with any other bacterial lineage. Its genetic materials have been extensively studied, particularly genes that relate to DNA repair and stress responses. Deinococcus Radiodurans can produce proteins that have been horizontally transferred from eukaryotic cells as efficient protection against proteome damage.
How is it Radiation- Resistant?
Cell death from radiation is not due to the damage of DNA, but rather radiation-induced protein damage that leads to inefficient repair of decayed DNA.
Deinococcus Radiodurans survives because it attains a highly efficient defence against proteome damage. Therefore, the cells can continue their turnover process through molecular repair of their own DNA. Furthermore, because there aren’t any opportunistic competitors, it permits lower mutation rates that enable the bacteria to endure the most difficult circumstances.
The Elephant’s Foot and Bioremediation
In 1986, the most radioactive place on the planet was sparked by the Chernobyl disaster. Experts have evaluated the area and determined that the ionizing radiation levels in the worst-hit areas of the reactor building have been estimated to be 5.6 roentgens per second, equivalent to more than 20,000 roentgens per hour.
Underneath the main reactor core in the plant, there is a massive mound of molten radioactive chromium weighing in at an estimated 2.2 tonnes. It is commonly known as the ‘elephant’s foot’. At it’s time of discovery, 8 months after the disaster, it was found that the radioactivity near the elephant’s foot was approximately 8000-10000 roentgens.
It is estimated that it could deliver a lethal dose of radiation that would cause severe cell damage within two minutes, and five minutes would result in death. However, people were amazed to find a fungal species called Cryptococcus neoformans growing around the Elephant’s Foot, reducing the radiation it diffuses.
This is a breakthrough in science, potential bioremediation of radioactive waste by employing the use of living organisms to decontaminate affected areas. Scientists believe that these extreme species could be a new way to naturally dispose of radioactive waste by absorbing or eating the radiation produced. This is only the start though, with scientists looking into potentials for these microbes for protection as well as disposal with hopes to use them as barriers to absorb radiation. There is extensive research being carried out to see if melanin can support fungi in extreme conditions and exploit ionising radiation.