Microbiology researchers trying to uncover the secret of the success of the dangerous food poisoning bacterium E. coli O157 have discovered that it uses a unique iron-gathering trick that may help it to overcome our bodies’ defenses.

Part of the normal way our bodies fight off bacteria and other disease threats is by withdrawing supplies of iron from our tissues iron, which is vital for the bacteria’s growth and reproduction. Some very dangerous bacteria overcome this defense mechanism by specifically targeting supplies of iron in our bodies.

Scientists at the University of Reading have discovered that the dangerous O157 strain of the common E. coli bacterium possesses an iron transporter, which is mutated and non-functional in the closely related but harmless K-12 strain that lives in our gut.

"The presence of the active form of this transporter in E. coli O157 appears to give the bacterium a special advantage when operating in low-iron, acid conditions conditions that may reflect those experienced inside the human host", says Jieni Cao from the School of Biological Sciences at the University of Reading, who made the discovery. "This could allow the food poisoning strain of E. coli to grow and multiply quickly during infection".

The researchers hope that by identifying the unique way the bacteria operate they will have also discovered a new target for antibacterial treatments in the future. A key component of the iron transporting system is similar to iron-uptake systems in some fungi, such as Candida, which causes thrush.