New research from Arizona State University reveal shocking methods bacteria can transfer with out their flagella — the slender, whip-like propellers that often drive them ahead.
Movement lets bacteria type communities, unfold to new locations or escape from hazard. Understanding how they do it will possibly assist us develop new instruments to battle in opposition to infections.
In the primary examine, Navish Wadhwa and colleagues present that salmonella and E. coli can transfer throughout moist surfaces even when their flagella are disabled. As half of their metabolism, the bacteria ferment sugars and arrange tiny outward currents on the moist floor. These currents carry the colony ahead, like leaves drifting on a skinny stream of water.
The researchers name this new type of motion “swashing.” It could assist clarify how dangerous microbes efficiently colonize medical units, wounds or food-processing surfaces. Understanding how metabolism drives bacterial motion may assist researchers develop new methods to restrict infections, for instance by altering native pH or sugar availability.
“We were amazed by the ability of these bacteria to migrate across surfaces without functional flagella. In fact, our collaborators originally designed this experiment as a ‘negative control,’ meaning that we expected (once rendered) flagella-less, the cells to not move,” Wadhwa says. “But the bacteria migrated with abandon, as if nothing were amiss, setting us off on a multiyear quest to understand how they were doing it.
“It just goes to show that even when we think we’ve got something figured out, there are often surprises waiting just under the surface, or in this case, above it.”
Wadhwa is a researcher with the Biodesign Center for Mechanisms of Evolution and assistant professor with the Department of Physics at ASU.
The study appears in the Journal of Bacteriology. The paper has been selected by the journal as an Editor’s Pick, highlighting the importance of the research.
Sugar-fueled swashing
When bacteria feed on sugars like glucose, maltose or xylose, they sometimes give off acidic by-products such as acetate and formate. These by-products draw water from the surface, creating currents that push the bacteria outward. Fermentable sugars are essential for this process — without them, the microbes can’t move in this way. Sugar-rich environments in the body, such as mucus, may actually help harmful bacteria spread and cause infection.
When researchers added detergent-like molecules known as surfactants to the colonies, the bacteria stopped swashing. In contrast, surfactants did not affect swarming, a coordinated, flagella-powered form of movement that lets bacteria spread rapidly across moist surfaces. This suggests the two forms of movement use distinct physical mechanisms, and that surfactants that can be used to selectively suppress (or enhance) the movement of bacteria depending on whether they are swashing or swarming.
The fact that bacteria can colonize surfaces even when their normal swimming machinery is impaired has important implications for human health. Some microbes may spread by swashing across medical catheters, implants and hospital equipment. Blocking flagella alone may not be enough to stop them. Instead, we may need to interfere with the chemical processes they use to power this movement.
Why this research matters
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Both E. coli and salmonella can cause foodborne illness. Knowing they can spread on surfaces through passive fluid flows may help improve how food processing plants design cleaning protocols. And because swashing depends on fermentation and acidic by-products, strategies that alter surface pH or sugar availability could reduce bacterial colonization. The study showed that simple changes in acidity were enough to alter how the bacteria moved.
Something similar may also occur inside the body, where moist surfaces like gut mucus, wound fluids or the urinary tract create favorable conditions for bacteria. In these places, bacteria could use swashing to spread even when their flagella don’t work well.
Shifting strategies
In a second study, corresponding author Abhishek Shrivastava and his colleagues checked out a sort of bacteria often known as flavobacteria. Unlike E. coli, these bacteria don’t swim; relatively, they navigate environmental and host-associated surfaces utilizing a machine referred to as the sort 9 secretion system, or T9SS, which propels a molecular conveyor belt.
Normally, the T9SS helps these bacteria glide throughout surfaces. It does this by transferring an adhesive-coated belt across the cell physique, pulling the bacterium ahead like a microscopic snowmobile. The researchers found {that a} conveyor-belt protein referred to as GldJ acts like a gear-shifter, controlling the route of this rotary motor.
If a small half of GldJ is deleted, the motor flips its spin from counterclockwise to clockwise, altering how the bacteria transfer. The examine describes this molecular gearset intimately and exhibits the way it permits bacteria to fine-tune their route of motion, giving them an evolutionary edge in navigating complicated environments.
Beyond enabling bacterial motion, the T9SS additionally has main implications for human well being — serving each dangerous and helpful roles relying on the microbial neighborhood. In the human oral microbiome, T9SS-containing bacteria are linked to gum illness, the place their secreted proteins promote irritation within the mouth and mind, contributing to issues comparable to heart disease and Alzheimer’s. Conversely, within the intestine microbiome, T9SS-secreted proteins can shield antibodies from degradation, thereby strengthening immunity and improving the efficacy of oral vaccines.
Understanding how this gearbox works may assist scientists design methods to block bacteria from forming slimy bacterial communities often known as biofilms, inflicting infections and contaminating medical units, but additionally harness its helpful properties to promote well being and develop focused microbiome therapies.
“We are very excited to have discovered an extraordinary dual-role nanogear system that integrates a feedback mechanism, revealing a controllable biological snowmobile and showing how bacteria precisely tune motility and secretion in dynamic environments,” Shrivastava says. “Building on this breakthrough, we now aim to determine high-resolution structures of this remarkable molecular conveyor to visualize, at atomic precision, how its moving parts interlock, transmit force and respond to mechanical feedback. Unraveling this intricate design will not only deepen our understanding of microbial evolution but also inspire the development of next-generation bioengineered nanomachines and therapeutic technologies.”
Shrivastava is a researcher with the Biodesign Center for Fundamental and Applied Microbiomics, the Biodesign Center for Mechanisms of Evolution, and assistant professor with ASU’s School of Life Sciences. The research seems within the journal mBio.
At first look, the 2 discoveries — fluid browsing and molecular gear-shifting, appear worlds aside. But they share a standard theme: bacteria have advanced a number of, shocking methods to unfold. The extra methods bacteria have, the more durable they’re to include.
The new findings additionally underscore the necessity for recent considering in combating bacterial illness. Many conventional approaches have usually centered on concentrating on flagella. But as these research present, bacteria can get round that limitation.
The analysis means that controlling the bacterial setting, together with components like sugar ranges, pH and floor chemistry, could also be simply as essential as concentrating on bacterial genes. And disrupting key molecular machines just like the T9SS gearbox may stop bacteria not solely from transferring but additionally from secreting the proteins that make them harmful.