How superbugs rapidly evolve

12-Oct-2018 - United Kingdom

A scientific breakthrough has revealed a new way that bacteria evolves, thought to be at least 1,000 times more efficient than any currently known mechanism. The insights will help scientists to better understand how superbugs can rapidly evolve and become increasingly antibiotic resistant.

The research, led by the University of Glasgow and the National University of Singapore and published in Science, has found a previously unknown method of genetic transduction – the process through which bacteria begins to evolve into potentially deadly superbugs.

The new process has been named Lateral Transduction, and now joins the two known methods of transduction: Generalised and Specialised Transduction, both discovered by the American scientist Joshua Lederberg, who won the Nobel Prize in Physiology or Medicine for his work with bacteria.

Working with the bacteria Staphylococcus aureus, scientists were able to demonstrate that this new naturally occurring method of transduction was at least one thousand times more efficient than generalised transduction, the best currently known method.

Due to the efficiency of lateral transduction, scientists speculate it is likely to be the most impactful type of transduction to occur in bacteria during its evolutionary process.

Professor José R Penadés, from the University of Glasgow, said: “This is an incredibly exciting and significant discovery. We have been able to show a new way that bacteria evolve. With the rise of superbugs that are increasingly antibiotic resistant, the importance of understanding the mechanisms for bacterial evolution has never been so important.

“Lateral transduction is an entirely natural process and we believe it also occurs in bacteria other than Staphylococcus aureus. This is a game-changer in terms of the way we understand bacterial evolution.”

Bacterial transduction is a process that involves viruses infecting bacteria. As a consequence of this mechanism, bacterial DNA moves from one to another bacteria, thereby causing mutation and evolution, often producing increasingly deadly and antibiotic resistant bugs.

Lateral transduction is unique in its efficiency. The process involves so many genes being transferred, that scientists have theorised whole sections of bacterial chromosome are being mobilised to other bacteria at the same time. This could help to explain the rapid pace at which superbugs are able to evolve.

This research also challenges current scientific thinking in this area, which assumes that only mobile genetic elements, but not the bacterial chromosomes, can be transferred at high frequencies. Now scientists believe lateral transduction has the power to move whole sections of bacterial chromosome including particularly deadly sections called pathogenic islands responsible for virulence and antibiotic resistance.

Assistant Professor John Chen, from the National University of Singapore, said: “Phages are by far the most abundant biological entities on the planet, and the importance of genetic transduction as one of the principle drivers of microbial evolution has never been more apparent than with the discovery of lateral transduction.”

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