E coli still deadly even after DNA sabotage
Research may explain bacteria’s danger to humans
SCIENTISTS have discovered that the potentially deadly E coli bacteria are hardwired for survival and can recover from attacks to their DNA patterns.
In a development that may help explain why our immune systems cannot always prevent infections, studies of the common E coli bug at the University of Edinburgh have shown it is able to recover continually from potentially fatal harm to its genetic material, without slowing down the rate at which it grows. Researchers said their discovery helps explain why bacteria are so hard to kill and why they are so widespread.
E coli are bacteria found in the digestive systems of many animals, including humans. Most strains are harmless but some can cause serious illness.
Dr Elise Darmon of the University of Edinburgh’s School of Biological Sciences, who led the study, said: “E coli has a robust approach to recover from DNA damage, which ensures an excellent survival rate. This study shows how tough bacteria are and why they are the most populous independent lifeform on Earth. More work is needed to determine whether their appetite for recovery is linked to bacteria’s ability to get the better of our immune systems.”
The team looked at how E coli responded when its DNA strands were deliberately broken as it tried to carry out its everyday function of dividing and reproducing.
They were surprised to find E coli able to use a combination of methods to survive repeated DNA damage.
It has an in-built emergency response to ensure that DNA damage is quickly repaired. In addition, it carries out overlapping rounds of DNA replication, which enables its cells to continue to divide and reproduce. This ensures E coli keeps multiplying as it recovers.
In experiments, the bacteria were able to thrive indefinitely and grow at similar rates, even when repeated DNA breaks took place.
Damage occurs in most organisms, for example from exposure to UV radiation or harmful chemicals.
And disease-causing
bacteria have to survive attacks from our immune system, which can lead to DNA damage. If not repaired, this can be fatal to bacteria.
Dr Darmon added: “There is a real need for new ways to kill pathogenic bacteria. Bacteria are the most populous organisms in the world – for example, there are ten times more bacteria cells in our bodies than there are human cells.”
She added: “This study shows how robust E coli can be and it is possible that other bacteria are similarly capable of recovering from damage.”
The study is published in the journal Plos One.