Thrust and Power Output of the Bacterial Flagellar Motor: A Micromagnetic Tweezers Approach

Abstract

One of the most common swimming strategies employed by microorganisms is based on the use of rotating helical filaments, called flagella, that are powered by molecular motors. Determining the physical properties of this propulsive system is crucial to understanding the behavior of these organisms. Furthermore, the ability to dynamically monitor the activity of the flagellar motor is a valuable indicator of the overall energetics of the cell. In this work, inherently magnetic bacteria confined in micromagnetic CoFe traps are used to directly and noninvasively determine the flagellar thrust force and swimming speed of motile cells. The technique permits determination of the ratio of propulsive force/swimming speed (the hydrodynamic resistance) and the power output of the flagellar motor for individual cells over extended time periods. Cells subjected to ultraviolet radiation are observed to experience exponential decays in power output as a function of exposure time. By noninvasively measuring thrust, velocity, and power output over time at a single-cell level, this technique can serve as the foundation for fundamental studies of bacterial hydrodynamics and also provides a novel, to our knowledge, tether-free probe of single-cell energetics over time.

Precisely Navigated Biobot Swarms of Bacteria Magnetospirillum magneticum for Water Decontamination

“…M. magneticum AMB-1 has helical structure flagella at either end of the cell, allowing it to swim forward or reverse directions through flagellar motion , and swim along the earth’s magnetic field through their magnetosomes produced within the cell (Video S1). , Therefore, precise direction control is essential to drive the bio-micro-/nanorobot through the interaction between M.…”

“…Micro-/nanorobots driven by magnetic fields, − light, , and acoustic fields have made it possible to improve various investigations of targeted drug delivery, , biosensing, − and environmental remediation. − In particular, magnetically driven biohybrid micro-/nanorobots are promising candidates in fields that require precise manipulation by integrating self-propulsion ability and magnetic actuation. − Propulsion using a magnetic field has advantageous features such as remote control, fuel-free propulsion, and programmability. − However, the integration of individual movements and the coherent orientation of the biohybrid micro-/nanorobots remains an important challenge. , …”