Several studies have shown that the absence of environmental radiation can impair the growth and functioning of various organisms, including bacteria, which is paradoxical given the harmful nature traditionally associated with ionising radiation. The mechanisms by which the lack of radiation affects bacterial physiology are still unknown, nor is its impact on the ability to adapt to antibiotics or environmental changes understood. Understanding these dynamics is essential, especially in scenarios where radiation levels differ from natural levels, such as in astrobiological contexts or space missions.
From an evolutionary perspective, it is reasonable to assume that species, including bacteria, have adapted to live under natural ranges of radiation, such that both an excess and a deficiency of radiation could lead to suboptimal conditions. To test this hypothesis, this study uses experimental evolution by subjecting populations of E. coli to extremely low environmental radiation conditions in the LSC and comparing them with controls kept on the surface. The degree of adaptation achieved, the costs associated with returning to normal radiation levels, and the influence of oxidative damage repair systems will be evaluated. In addition, how the absence of radiation modulates the evolution of antibiotic tolerance will be investigated, and the genetic variants responsible for adaptation will be identified through genome sequencing.