Migration between different communities of bacteria is the key to the type of gene transfer that can lead to the spread of traits such as antibiotic resistance, according to researchers at Oxford University. While horizontal gene transfer - also known as bacterial sex - has long been acknowledged as central to microbial evolution, why it is able to exert such a strong effect has remained a mystery. 

But now scientists from the Department of Zoology have demonstrated through mathematical modelling that the secret is migration, whereby movement between communities of microbes greatly increases the chances of different species of bacteria being able to swap DNA and adopt new traits.

The study, published in Nature Communications, sheds new light on how the spread of traits such as antibiotic resistance is able to happen.

Kevin Foster, Professor of Evolutionary Biology at Oxford University and principal investigator of the project, said: 'It is well known that bacteria are able to swap little pieces of DNA, which is crucial for them to be able to evolve and adapt to new environments, including responding to antibiotics. It's different to sex in humans, but the effect - swapping genetic material - is similar.

'However, sex in bacteria is a very rare event, with only one cell among millions swapping DNA. And in theory, any resistant strain will rapidly divide and take over the community, shutting down any opportunity to share the resistance gene with others. 

'But it does keep happening, and genes are often able to hop through diverse groups of different bacteria. Until now, the mystery has been why.'