Some bacteria travel in very small areas. Researchers—along with a researcher’s amazing illustration of a devil-may-care virus—have revealed how viruses. Caballeronia insecticola it is able to cut small channels in the digestive tract of bean insects.
In a study published last week in Nature Communications, a team of researchers found just that C. insecticola it moves through the bottle in the bug’s gut which is 1 micrometer in diameter with a “flagellar folding” movement. In this process, the microbe wraps its flagellum—the tail-like part that bacteria use to move themselves—around itself and develops like a rotating screw. The findings reveal how this species successfully navigates such a small passageway and could inform treatments for harmful bacteria.
‘Screw-thread’ configuration
“A few years ago, researchers noticed something unusual: C. insecticola sometimes it folds its flagella in front of its body instead of trailing it behind like a normal swimmer,” Daisuke Nakane, a University of Electro-Communications researcher and co-author of the study, wrote in the Behind the Paper article for Springer Nature. But was this strange movement just a curiosity—or was it the key to overcoming narrow spaces?”
According to Nakane, researchers have wondered about the species’ ability to navigate such small spaces for long periods of time. Nakane and his team were placed C. insecticola in a device with channels almost the same diameter as the original bottle. As you can see in the video below, viruses travel well on these restricted channels.
The wee beasties drastically changed their mobility to flagellar coiling. While about 15% of bacteria resorted to flagellar folding in wide chambers, 65% used it in narrow passages of researchers, and it took only a limited area to initiate the change. Computer simulations reveal the secret of this method’s success.
“In a narrow zone, the fluid around the cell does not move because the walls block it.” An extended flagellum—which tends to push water back—is almost useless,” explains Nakane. But a folded flagellum creates a rotating helical surface that squeezes fluid through the small gap between the cell and the wall. This creates a strong forward thrust, making the bacterium a self-propelled screw that’s perfect for a solid environment.”
Good law
Nakane and his colleagues found out that there was C. insecticola relatives do the same. Species that can use flagellar folding may sustain their speed as they move through narrow tunnels, while those that can’t slow down or sometimes stop altogether.
The researchers also showed that the bacterium’s ability to fold is in the hook, a flexible joint at the base of the flagellum that provides more or less flexibility depending on the species. The team confirmed their theory—that is C. insecticola has a flexible hook that allows for flagellar folding—by testing gene mutations.
When researchers change C. insecticolaflexible hook with a strong version from another species, the microbe can no longer use flagellar folding and ground to stand firm in hard surfaces. But if it is installed C. insecticolaA soft hook, some species may—at least to some extent—participate in folding the flagellum, allowing it to move over tight surfaces.
“Physics simulations have recapitulated these results, emphasizing a simple but beautiful rule: a flexible hook makes a bend; a bend makes a tunnel; a tunnel makes it survive,” said Nakane. “And this wasn’t just a laboratory thing. When we tested the stiff-hook mutants inside real bean bugs, their ability to colonize the host decreased. Without coiling, they couldn’t get past the one-micrometer threshold. Evolution had clearly shaped the flexibility of the hook to help the bacteria navigate the internal structures of their host.”
Flag folding club
Scientists noticed similar movements in similar organisms Campylobacterium, Helicobacteragain Pseudomonas-bacteria travel through glandular ducts and mucus membranes—suggesting that flagellar folding may be a common feature among bacteria that need to traverse thin and viscous surfaces.
Perhaps even more exciting, the ability to inhibit or amplify this strategy can slow down harmful bacteria and support beneficial ones. This intelligent gear shift may also encourage the setting up of nanoscale drilling systems or micro-robots.
