One small rotation for a bacterium...

If bacteria had engines, the flagellum would be their turbocharged propeller. Spinning at thousands of revolutions per minute, this tiny rotary machine allows bacteria to swim, sense their surroundings, and interact with hosts—all using a structure smaller than the wavelength of light. Few biological systems are as elegant, fast, and mechanically impressive as the bacterial flagellum. In this review, the Molecular Microbiology Group (Marc Erhardt) explores recent advances in understanding how the flagellum of Salmonella enterica is built, powered, and controlled. They highlight the coordinated gene regulation that governs its assembly, the mechanics of its motor, and new structural insights into its core components, while placing these findings in the broader context of bacterial diversity. They also outline open questions and argue that high-resolution, single-cell approaches will be key to fully understanding one of nature’s most sophisticated nanomachines. Check out their Review in Microbiology and Molecular Biology Reviews

Abstract

Bacterial flagella are remarkable rotary machines that enable motility, environmental sensing, and host interaction. In this review, we discuss recent advances in understanding the structure, assembly, and regulation of the flagellum in Salmonella enterica, emphasizing both common principles and distinctive features across bacteria. We discuss the hierarchical gene regulation, the dynamic mechanics of the motor, and recent structural insights into the flagellar core components. We also reflect on the legacy of Howard Berg, whose foundational work in Escherichia coli shaped much of what we know about bacterial locomotion in Gammaproteobacteria. His contributions, from flagellar rotation to chemotaxis and motor dynamics, transformed the field and continue to inspire current research into one of nature’s most intricate nanomachines. Finally, we highlight open questions that place bacterial motility within the broader context of cellular processes and call for detailed single-cell observations.