Two new studies from Arizona State University have identified surprising ways bacteria move without using their flagella. The discoveries, published in the Journal of Bacteriology and mBio, expand understanding of how microbes spread and persist in challenging environments, including medical and industrial settings.
In the first study, Navish Wadhwa and colleagues found that Salmonella and E. coli can travel across moist surfaces even when their flagella are disabled. The team discovered that as these bacteria ferment sugars, they generate acidic by-products such as acetate and formate. These compounds draw water to the surface, creating outward currents that carry the microbes forward. The researchers call this motion “swashing.”
“We were amazed by the ability of these bacteria to migrate across surfaces without functional flagella,” Wadhwa said. “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. 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.”
The finding suggests bacteria can colonize medical devices or food-processing surfaces even when their normal swimming machinery is disrupted. Experiments showed that surfactants stopped swashing but not flagella-driven swarming, indicating distinct physical mechanisms. Adjusting surface pH or sugar content could limit this movement and reduce bacterial colonization.
In a second study, Abhishek Shrivastava and his team investigated flavobacteria that move using a type 9 secretion system (T9SS). This system drives an adhesive conveyor belt along the cell body, propelling the bacteria forward. The researchers found that a protein called GldJ functions as a molecular gear, reversing the motor’s spin direction when part of it is deleted.
Shrivastava described the discovery as “an extraordinary dual-role nanogear system that integrates a feedback mechanism, revealing a controllable biological snowmobile.” The work shows that even without flagella, bacteria have evolved multiple mechanical strategies to move and adapt to their environments.
Publication Details
Panich J, Dudebout EM, Blair DF, Wadhwa N. 0. Swashing: a propulsion-independent form of bacterial surface migration. J Bacteriol 0:e00323-25.
https://doi.org/10.1128/jb.00323-25
Trivedi A, Miratsky JA, Henderson EC, Singharoy A, Shrivastava A. 2025. A molecular conveyor belt-associated protein controls the rotational direction of the bacterial type 9 secretion system. mBio 16:e01125-25.
https://doi.org/10.1128/mbio.01125-25
In the first study, Navish Wadhwa and colleagues found that Salmonella and E. coli can travel across moist surfaces even when their flagella are disabled. The team discovered that as these bacteria ferment sugars, they generate acidic by-products such as acetate and formate. These compounds draw water to the surface, creating outward currents that carry the microbes forward. The researchers call this motion “swashing.”
“We were amazed by the ability of these bacteria to migrate across surfaces without functional flagella,” Wadhwa said. “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. 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.”
The finding suggests bacteria can colonize medical devices or food-processing surfaces even when their normal swimming machinery is disrupted. Experiments showed that surfactants stopped swashing but not flagella-driven swarming, indicating distinct physical mechanisms. Adjusting surface pH or sugar content could limit this movement and reduce bacterial colonization.
In a second study, Abhishek Shrivastava and his team investigated flavobacteria that move using a type 9 secretion system (T9SS). This system drives an adhesive conveyor belt along the cell body, propelling the bacteria forward. The researchers found that a protein called GldJ functions as a molecular gear, reversing the motor’s spin direction when part of it is deleted.
Shrivastava described the discovery as “an extraordinary dual-role nanogear system that integrates a feedback mechanism, revealing a controllable biological snowmobile.” The work shows that even without flagella, bacteria have evolved multiple mechanical strategies to move and adapt to their environments.
Publication Details
Panich J, Dudebout EM, Blair DF, Wadhwa N. 0. Swashing: a propulsion-independent form of bacterial surface migration. J Bacteriol 0:e00323-25.
https://doi.org/10.1128/jb.00323-25
Trivedi A, Miratsky JA, Henderson EC, Singharoy A, Shrivastava A. 2025. A molecular conveyor belt-associated protein controls the rotational direction of the bacterial type 9 secretion system. mBio 16:e01125-25.
https://doi.org/10.1128/mbio.01125-25