KU Leuven researchers find bacteria DNA mutates under stress

In Belgium, bacteria need mutations or changes in their DNA code to survive under difficult circumstances. When necessary, they can even mutate at different speeds. This is shown in a recent study by the Centre of Microbial and Plant Genetics at KU Leuven. The findings open up various new avenues for research, ranging from more efficient biofuel production methods to a better treatment for bacterial infections and cancer.

When they’re under stress, bacteria start mutating to produce one or more DNA variants that make it possible for the bacteria to survive and reproduce. But mutating is dangerous under normal circumstances as it weakens the bacteria. The trick, therefore, is finding the balance between too many and too few mutations. Losing this balance means hypermutation: the cell mutates much more quickly than it normally does, eventually leading to death.

As scientific knowledge about the role of hypermutation is still limited, KU Leuven researchers examined its underlying mechanism in the gut bacteria Escherichia coli. “E.coli is a notorious cause of diarrhoea, but most E.coli strains are in fact harmless gut bacteria found in human beings and animals,” says Professor Jan Michiels. “Exposure to high, near-lethal concentrations of ethanol triggers hypermutation in the E.coli. We were surprised to find that the speed of hypermutation in the bacteria can rapidly be changed: the bacteria mutate more quickly in higher concentrations of ethanol and more slowly when the ethanol stress is relieved. As soon as the danger is past, the bacteria step on the brake and try to revert to their normal state, without hypermutation.”