By: Freya Preimsberger
In a study conducted by researchers at the University of Leuven, populations of Escherichia coli bacteria were found to modulate their mutation rates to survive when placed in stressful environments, contrasting with previous
By: Freya Preimsberger
In a study conducted by researchers at the University of Leuven, populations of Escherichia coli bacteria were found to modulate their mutation rates to survive when placed in stressful environments, contrasting with previous observations that mutations are slow to occur and heavily regulated by cells. According to the study, the findings may help to explain why cells mutate rapidly in certain situations, such as in the development of antibiotic-resistant bacteria or in the recurrence of cancer after treatment with chemotherapy. The researchers published their findings in eLife on May 2, 2017.
Mutations, which are changes in DNA sequence, can be neutral, beneficial or harmful to a cell’s biological fitness. Some mutations are necessary for survival in new or stressful environments, but random mutations often have neutral or deleterious effects and require more energy from the cell during replication. Because of this, cells are careful to modulate how many mutations they develop and typically maintain low genomic mutation rates. In some instances, cellular repair mechanisms that usually correct alterations in DNA fail, causing some cells to mutate more rapidly in a process called hypermutation. Hypermutation is found in some species of bacteria and in pathogenic fungi and parasites, and is an important process for cancer proliferation and tumor progression. These observations suggest that for certain environments, particularly harsh ones, hypermutation is advantageous for some cells’ survival. Hypermutation can lead to cell death, but it can also enable cells to adapt to quickly changing environments, serving as a crucial survival mechanism for microbes exposed to nearly-lethal conditions. Previous studies on hypermutation only looked at how microbes react under mildly stressful conditions, prompting researchers in the study to examine how bacteria mutate in high-stress, nearly-lethal conditions.
Researchers subjected samples of E. coli, which are bacteria found in the intestines of warm-blooded animals, to environments containing high concent