Researchers at Oxford University published a study that discovered why horizontal gene transfer, also referred to as bacterial sex, has such a strong effect on microbial evolution, as outlined in the press release. The study utilized mathematical modeling and found that the key is migration, which is when movement between microbe communities significantly increases the chances of different bacteria species' swapping DNA, thus leading to a higher likelihood of the adoption of new traits.

"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," said Kevin Poster, principal investigator of the project. "It's different to sex in humans, but the effect - swapping genetic material - is similar."

The Oxford University researchers studied a particular group of genes that are known to be carriers of antibiotic resistance called IncP-1 plasmids. After using advanced DNA analysis techniques, they were able to pinpoint the origin of these genes and paint a better picture of their mobility between various bacterial species.

"What we found was that the missing ingredient was migration," said René Niehus, lead author of the study. "Previous work ignored that these communities are open, and our model shows that this very high immigration rate among bacteria gives a huge opportunity for different microbes to meet and swap DNA, even though it's a rare event when taken in isolation."

The process of bacterial migration can take place almost anywhere - from inside ground soil to the human body - and this migration can pass beneficial traits horizontally between microbes and stimulate evolution. Some of these beneficial traits include antibiotic resistance, particular nutrients or the ability to survive an environmental toxin.

"The key point is that a bacterial system with continual immigration of strains will allow traits like antibiotic resistance to spread much more easily between different species of bacteria," said Niehus. "Our model offers a theoretical framework for understanding the processes behind this spread."