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A study reveals how bacteria assemble their 'electric motors' to move

A research team from the Andalusian Center for Developmental Biology identifies how the bacterium Pseudomonas putida ensures the mobility of its daughter cells after cell division.

Understanding how this machinery is formed could open the door to new strategies to control pathogenic bacteria or improve the performance of beneficial bacteria in agriculture and biotechnology.

A research team from the Andalusian Center for Developmental Biology (CABD) has taken a step forward in understanding the complex machinery that allows bacteria to move in their environment. In a recent study, led by the researcher of the Microbiology Area of the Pablo de Olavide University Fernando Govantes and recently published in the journal Microbiological Research, the team has unveiled the molecular mechanisms that regulate the assembly and positioning of flagella, tiny helix-shaped structures that function as 'electric motors' in these cells.

Bacterial flagella are essential for the mobility of many microorganisms, which use them to escape adverse conditions and explore new habitats. “Each bacterial species displays flagella in a characteristic number and location. The well-known Escherichia coli has peritrichous flagellation, i.e., multiple flagella over its entire surface. In these bacteria, after cell division, each of the daughter cells inherits half of the flagella of the mother cell,” explains Fernando Govantes, UPO researcher and head of the ‘Genetics of bacterial biofilm development’ group at the CABD, a joint center of the Spanish National Research Council (CSIC), the Pablo de Olavide University and the Andalusian Regional Government.

“Other bacteria, on the other hand, have one or more flagella on only one of their poles,” adds the researcher, ”so in these bacteria, sharing is impossible, so one of the daughter cells inherits the flagellum or flagella of the parent cell.” So how do these bacteria ensure that the two daughter cells are equipped with the flagella that correspond to their species?

The work of the CABD team has studied this problem in the bacterium Pseudomonas putida, known for its ability to colonize soils and plant roots and contribute to agriculture and the improvement of environmental quality. In their case, the flagella are clustered at one pole of the cell, forming a tuft of between three and six units.



Flagella of Pseudomonas putida under the microscope. In red, cell membrane; in green, flagella.

A key finding in bacterial biology

The study reveals how Pseudomonas putida is able to make new flagella at its 'new' pole (created after cell division) while retaining the flagella inherited from the 'old' pole. This process ensures that both daughter cells have the ability to move, even in cases where they do not directly inherit flagella from the parent cell.

The work identifies three key proteins in this process: FleN, FlhF and FimV. These molecules act as building blocks in determining how many flagella are made, where they are positioned and when they are assembled. In particular, the FimV protein functions as a 'molecular beacon', guiding the assembly machinery to the right place and ensuring that new flagella emerge just at the time of cell division, with this new function of the FimV protein being one of the central findings of this study.


Life cycle of a bacterium with polar flagella. After each cell division, FimV, FlhF and FleN proteins accumulate in the new pole of Pseudomonas putida to coordinate where, when and how many flagella to make in the new daughter cell.


According to the researchers, this mechanism of spatial, temporal and numerical regulation is a fascinating example of biological precision, comparable to the functioning of a molecular clock. “The ability to make flagella in the right place at the right time is essential for the survival of many bacteria. This process, far from being random, is finely controlled at the molecular level,” explains Marta Pulido-Sánchez, lead author of the study.



Marta Pulido-Sánchez, the first author of the published study.

Significance of the finding

The study not only expands our understanding of how bacteria manage to move, but also has broader implications for molecular biology and evolution. With respect to bacterial motility and habitat colonization, it is noteworthy that flagella allow bacteria to colonize complex environments, including agricultural soils and living organisms. Understanding how this machinery is formed could open the door to new strategies to control pathogenic bacteria or improve the performance of beneficial bacteria in agriculture and biotechnology.

On the other hand, the finding also sheds light on another phenomenon, cell polarity generation, which refers to the differentiation between the ends of a cell. This concept, common in complex organisms, has its roots in processes such as that observed in bacteria, which helps to understand the evolutionary origins of more advanced cellular structures and functions.

Next steps in research

The research team plans to delve deeper into several open questions, concerning the magnitude of cell polarity phenomena, the synchronization of flagella assembly with the cell cycle, or the molecular differences that explain why some bacteria make several flagella and others only one.

According to the authors, small variations in the proteins involved could be responsible for the diversity of flagellation patterns observed in nature. This raises new questions about the relationship between flagella structure, habitat and lifestyle of individual bacteria.

Study reference:
Marta Pulido-Sánchez, Antonio Leal-Morales, Aroa López-Sánchez, Felipe Cava, Fernando Govantes. Spatial, temporal and numerical regulation of polar flagella assembly in Pseudomonas putida. Microbiological Research. 2025. DOI: https://doi.org/10.1016/j.micres.2024.128033