Earth is not home only to the most intelligent species known: humans. The planet also harbors organisms that are able to survive under very harsh conditions like extremely low temperatures, radiation, space vacuum, and more. Also known as extremophiles, these creatures are microscopic. The strongest extremophiles are the bacterium Deinococcus radiodurans.
Scientists remain puzzled as they can’t fully explain how radio-resistance (the level of ionizing radiation that organisms can endure) could have evolved for several organisms. There are some scientists suggesting that radio-resistance in extremophiles could have evolved along with other kinds of resistance. But yet a great question remains: which genes are involved in radio-resistance?
Ask the cells themselves
A team of Dr. Cox from the University of Wisconsin-Madison, started to expose E. coli to 50 rounds of ionization. After about 10 rounds, radio-resistant populations emerged. After 50 rounds, the study of genetic profile highlighted three mutations that are responsible for radio-resistance.
The scientists even started with the naturally non-resistant bacteria known as E. coli, exposing it to high-level irradiation. After many rounds of exposure, a few radio-resistant populations appeared. By using whole-genome sequencing, the researchers were able to study genetic alterations present in the radio-resistant populations and determined mutations that provided radio-resistance to the bacteria.
Dr. Cox declared:
“The four populations we are evolving in this new trial have now achieved levels of radio-resistance that are approaching the levels seen with Deinococcus radiodurans. As the current trial has progressed, the genomic alterations have proven to be much more complex than anticipated.”
The radioresistant E. coli continued to evolve by also creating sub-populations. The second induced hundreds of mutations included large deletions and duplications of genes, although radio-resistance induced by the first series of ionization could be associated firstly with three mutations.
The results were published in Frontiers in Microbiology.