BBC News Online: Sci/Tech

Cooking up new antibiotics

An exciting new molecule capable of killing drug-resistant superbugs has been discovered in a loaf of sourdough bread.

The molecule is made by a lactic acid bacterium called Lactobacillus reuteri, which is also found in the human intestine.

Recent research supports the long-held belief that eating lactic acid bacteria, especially those in live yoghurt, is good for you. However, researchers are still trying to find out why.

These bacteria are also vital in making and preserving fermented foods because they can kill off disease-causing bugs.

The latest discovery came when Dr Michael Gänzle, a food researcher at Hohenheim University, Germany, noticed the strain of L. reuteri he was using in sourdough bread was killing off more microbes than usual.

He isolated the molecule responsible and had it examined by Dr Alexandra Höltzel at the University of Tübingen.

Antibiotic hope

The molecule, dubbed reutericyclin, turned out to be a new and unique type of tetramic acid. It is completely different from any other molecule lactic bacteria usually make, which may explain why it has never been noticed before. It is also possible that reutericyclin is only made by the particular laboratory strain Dr Gänzle was using.

In laboratory tests, reutericyclin decimates super-bugs that are resistant to most antibiotics. This could spell good news for the medical world as antibiotic resistance is increasing worldwide and fast becoming a major health problem.

However, there may be a sting in the tale: the only other known tetramic acid similar to reutericyclin is toxic.

University spin-off company EMC Microcollections Tübingen is hard at work determining if reutericyclin is toxic and if it can be used to treat harmful bacterial infections.

Dr David Livermore, an expert on antibiotic resistance at the UK's Central Public Health Laboratory, gives reutericyclin a cautious welcome. He told BBC News Online: "Finding any new antibiotic family is interesting. But it's early days for this one, and the development of any new drug for human use is slow and expensive, with ultimate success uncertain."

The reutericyclin research is published in Angewandte Chemie International.