In a study published today in Nature Communications, scientists have deciphered how some types of “swimming” bacteria have evolved to be able to escape when trapped in small spaces. The discovery could pave the way to finding new methods to stop the spread of certain bacteria, including species that cause food poisoning and stomach ulcers.
Many bacteria can swim, allowing them to seek out new sources of nutrients, or in the case of pathogenic bacteria, infect and spread. Almost all swimming species of bacteria propel themselves forward using corkscrew-like propellers called “flagella.” Bacterial flagella are composed of thousands of protein building blocks arranged in spiraling chains.
A multidisciplinary team of scientists has discovered that some types of bacteria have evolved complex flagella made up of many different types of proteins. Looking at a soil-dwelling species of bacteria called Shewanella putrefaciens, they found that when these bacteria get stuck in a tight space, their multi-component flagella buckle, wrapping around the cell bodies and allowing them to corkscrew free.
“The question of why some bacteria such as E. coli have flagella made up of one type of protein while others have more complicated flagella made up of many different types has been a longstanding mystery,” says co-author Dr. Laurence Wilson of the University of York. “Nature likes to keep things simple. In any ‘machine,’ more components mean more things that could go wrong. Our study has shown that complicated flagella have a function which helps bacteria escape when they get stuck in tight spaces, an advantage which outweighs the cost of maintaining genes to encode the various protein building blocks.”
Using computer simulations, the team also found that the building blocks in the flagella of Shewanella putrefaciens are arranged optimally. When the scientists removed or swapped the flagella components, the bacteria’s ability to swim, whether in “open waters” or in tight spaces, was impaired.
“Species of bacteria such as Campylobacter jejuni, which causes food poisoning, and Helicobacter pylori, which causes stomach ulcers, have been found to maintain multiple components in their flagella,” Wilson adds. “This study gives us a better understanding of the physics of bacterial infection—knowledge which could lead to new ways of blocking the transmission of harmful infections in the future.”