scholarly journals Orientation fluctuations in magnetotactic swimming

2021 ◽  
Author(s):  
Sebastian Smyk ◽  
Vitali Telezki ◽  
Josef Riepl ◽  
Johannes Hayes ◽  
Stefan Klumpp
Keyword(s):  
Magnetic Field ◽  
Effective Temperature ◽  
Correlation Time ◽  
Thermal Noise ◽  
Internal Noise ◽  
Magnetotactic Bacteria ◽  
Noise Contribution

AbstractThe fluctuations experienced by magnetic microswimmers in a magnetic field often have non-thermal contributions, in particular in the case of biological swimmers such as magnetotactic bacteria. Here we study a model for an active self-propelled particle subject to correlated internal noise as a model for the active, non-thermal noise contribution and determine the effect of the correlation time on the diffusion of the swimmer and on its orientation in a magnetic field. A description in terms of an effective temperature is possible, but has limitations.

scholarly journals Magnetotaxis as a Means for Nanofabrication

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1450008
Author(s):  
Isaac Macwan ◽  
Zihe Zhao ◽  
Omar Sobh ◽  
Jinnque Rho ◽  
Ausif Mahmood ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Semiconductor Manufacturing ◽  
Magnetic Field Intensity ◽  
Magnetotactic Bacteria ◽  
Semiconductor Substrate ◽  
Field Lines ◽  
A Chain ◽  
Magnetospirillum Magneticum ◽  
The Magnetic Field

Magnetotactic bacteria (MTB), discovered in early 1970s contain single-domain crystals of magnetite ( Fe 3 O 4) called magnetosomes that tend to form a chain like structure from the proximal to the distal pole along the long axis of the cell. The ability of these bacteria to sense the magnetic field for displacement, also called magnetotaxis, arises from the magnetic dipole moment of this chain of magnetosomes. In aquatic habitats, these organisms sense the geomagnetic field and traverse the oxic-anoxic interface for optimal oxygen concentration along the field lines. Here we report an elegant use of MTB where magnetotaxis of Magnetospirillum magneticum (classified as AMB-1) could be utilized for controlled navigation over a semiconductor substrate for selective deposition. We examined 50mm long coils made out of 18AWG and 20AWG copper conductors having diameters of 5mm, 10mm and 20mm for magnetic field intensity and heat generation. Based on the COMSOL simulations and experimental data, it is recognized that a compound semiconductor manufacturing technology involving bacterial carriers and carbon-based materials such as graphene and carbon nanotubes would be a desirable choice in the future.

scholarly journals A Compass To Boost Navigation: Cell Biology of Bacterial Magnetotaxis

2020 ◽  
Vol 202 (21) ◽  
Author(s):  
Frank D. Müller ◽  
Dirk Schüler ◽  
Daniel Pfeiffer
Keyword(s):  
Magnetic Field ◽  
Cell Biology ◽  
Molecular Mechanisms ◽  
Magnetotactic Bacteria ◽  
Genetically Engineered ◽  
Model Organisms ◽  
Complex Cell ◽  
Magnetite Biomineralization ◽  
Directed Motility ◽  
The Impact

ABSTRACT Magnetotactic bacteria are aquatic or sediment-dwelling microorganisms able to take advantage of the Earth’s magnetic field for directed motility. The source of this amazing trait is magnetosomes, unique organelles used to synthesize single nanometer-sized crystals of magnetic iron minerals that are queued up to build an intracellular compass. Most of these microorganisms cannot be cultivated under controlled conditions, much less genetically engineered, with only few exceptions. However, two of the genetically amenable Magnetospirillum species have emerged as tractable model organisms to study magnetosome formation and magnetotaxis. Recently, much has been revealed about the process of magnetosome biogenesis and dedicated structures for magnetosome dynamics and positioning, which suggest an unexpected cellular intricacy of these organisms. In this minireview, we summarize new insights and place the molecular mechanisms of magnetosome formation in the context of the complex cell biology of Magnetospirillum spp. First, we provide an overview on magnetosome vesicle synthesis and magnetite biomineralization, followed by a discussion of the perceptions of dynamic organelle positioning and its biological implications, which highlight that magnetotactic bacteria have evolved sophisticated mechanisms to construct, incorporate, and inherit a unique navigational device. Finally, we discuss the impact of magnetotaxis on motility and its interconnection with chemotaxis, showing that magnetotactic bacteria are outstandingly adapted to lifestyle and habitat.

scholarly journals Biomagnetic Recovery and Bioaccumulation of Selenium Granules in Magnetotactic Bacteria

2016 ◽  
Vol 82 (13) ◽  
pp. 3886-3891 ◽  
Author(s):  
Masayoshi Tanaka ◽  
William Knowles ◽  
Rosemary Brown ◽  
Nicole Hondow ◽  
Atsushi Arakaki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Particles ◽  
Magnetotactic Bacteria ◽  
Selenium Nanoparticles ◽  
Water Remediation ◽  
Polluted Water ◽  
Contaminated Water ◽  
Elemental Selenium ◽  
Cell Recovery

ABSTRACTUsing microorganisms to remove waste and/or neutralize pollutants from contaminated water is attracting much attention due to the environmentally friendly nature of this methodology. However, cell recovery remains a bottleneck and a considerable challenge for the development of this process. Magnetotactic bacteria are a unique group of organisms that can be manipulated by an external magnetic field due to the presence of biogenic magnetite crystals formed within their cells. In this study, we demonstrated an account of accumulation and precipitation of amorphous elemental selenium nanoparticles within magnetotactic bacteria alongside and independent of magnetite crystal biomineralization when grown in a medium containing selenium oxyanion (SeO32−). Quantitative analysis shows that magnetotactic bacteria accumulate the largest amount of target molecules (Se) per cell compared with any other previously reported nonferrous metal/metalloid. For example, 2.4 and 174 times more Se is accumulated than Te taken up into cells and Cd2+adsorbed onto the cell surface, respectively. Crucially, the bacteria with high levels of Se accumulation were successfully recovered with an external magnetic field. The biomagnetic recovery and the effective accumulation of target elements demonstrate the potential for application in bioremediation of polluted water.IMPORTANCEThe development of a technique for effective environmental water remediation is urgently required across the globe. A biological remediation process of waste removal and/or neutralization of pollutant from contaminated water using microorganisms has great potential, but cell recovery remains a bottleneck. Magnetotactic bacteria synthesize magnetic particles within their cells, which can be recovered by a magnetic field. Herein, we report an example of accumulation and precipitation of amorphous elemental selenium nanoparticles within magnetotactic bacteria independent of magnetic particle synthesis. The cells were able to accumulate the largest amount of Se compared to other foreign elements. More importantly, the Se-accumulating bacteria were successfully recovered with an external magnetic field. We believe magnetotactic bacteria confer unique advantages of biomagnetic cell recovery and of Se accumulation, providing a new and effective methodology for bioremediation of polluted water.

Wastewater treatment by bio-magnetic separation: a comparison of iron oxide and iron sulphide biomass recovery

1998 ◽  
Vol 38 (6) ◽  
pp. 311-317 ◽  
Author(s):  
A. S. Bahaj ◽  
P. A. B. James ◽  
F. D. Moeschler
Keyword(s):  
Magnetic Field ◽  
Iron Oxide ◽  
Magnetic Separation ◽  
Magnetotactic Bacteria ◽  
Water Systems ◽  
Processing Conditions ◽  
Iron Sulphide ◽  
Single Wire ◽  
Biomass Recovery ◽  
Reducing Bacteria

Many microorganisms have an affinity to accumulate metal ions onto their surfaces, which results in metal loading of the biomass. Microbial biomineralisation of iron produces a biomass, which is often highly magnetic and can be separated from water systems by the application of a magnetic field. This paper reports on the magnetic separation of biomass containing microbial iron oxide (Fe3O4, present within magnetotactic bacteria) and iron sulphide (Fe1-XS, precipitated extracellularly by sulphate reducing bacteria) in a single wire cell. Since such bacteria can be separated magnetically, their affinity to heavy metal or organic material accumulation renders them useful for the removal of pollutants from wastewater. The relative merits of each bacterium to magnetic separation techniques in terms of applied magnetic field and processing conditions are discussed.

scholarly journals Measuring the Effective Temperature of Single Magnetotactic Bacteria as a Tool to Study Non-Thermal Biological Noise

2018 ◽  
Vol 114 (3) ◽  
pp. 328a-329a
Author(s):  
Lucas Le Nagard ◽  
Solomon Barkley ◽  
Xiaohui Zhu ◽  
Adam P. Hitchcock ◽  
Cecile Fradin
Keyword(s):  
Effective Temperature ◽  
Magnetotactic Bacteria ◽  
Biological Noise

scholarly journals Stokesian dynamics simulations of a magnetotactic bacterium

2021 ◽  
Vol 44 (3) ◽  
Author(s):  
Sarah Mohammadinejad ◽  
Damien Faivre ◽  
Stefan Klumpp
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Cell Body ◽  
Magnetic Moment ◽  
Magnetotactic Bacteria ◽  
Swimming Velocity ◽  
Stokesian Dynamics ◽  
Inclination Angles ◽  
Dynamics Simulations ◽  
The Magnetic Field

AbstractThe swimming of bacteria provides insight into propulsion and steering under the conditions of low-Reynolds number hydrodynamics. Here we address the magnetically steered swimming of magnetotactic bacteria. We use Stokesian dynamics simulations to study the swimming of single-flagellated magnetotactic bacteria (MTB) in an external magnetic field. Our model MTB consists of a spherical cell body equipped with a magnetic dipole moment and a helical flagellum rotated by a rotary motor. The elasticity of the flagellum as well as magnetic and hydrodynamic interactions is taken into account in this model. We characterized how the swimming velocity is dependent on parameters of the model. We then studied the U-turn motion after a field reversal and found two regimes for weak and strong fields and, correspondingly, two characteristic time scales. In the two regimes, the U-turn time is dominated by the turning of the cell body and its magnetic moment or the turning of the flagellum, respectively. In the regime for weak fields, where turning is dominated by the magnetic relaxation, the U-turn time is approximately in agreement with a theoretical model based on torque balance. In the strong-field regime, strong deformations of the flagellum are observed. We further simulated the swimming of a bacterium with a magnetic moment that is inclined relative to the flagellar axis. This scenario leads to intriguing double helical trajectories that we characterize as functions of the magnetic moment inclination and the magnetic field. For small inclination angles ($$\lesssim {20^{\circ }}$$≲20∘) and typical field strengths, the inclination of the magnetic moment has only a minor effect on the swimming of MTB in an external magnetic field. Large inclination angles result in a strong reduction in the velocity in direction of the magnetic field, consistent with recent observations that bacteria with large inclination angles use a different propulsion mechanism.Graphic abstract

Sensing of Local, Highly Concentrated Magnetic Field Gradients in Magnetotactic Bacteria Induces Motility Reversal

2012 ◽  
Author(s):  
Lina M. González ◽  
Warren C. Ruder ◽  
William C. Messner ◽  
Philip R. LeDuc
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetotactic Bacteria ◽  
Chemical Gradients ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Direction Of Movement ◽  
Unicellular Organisms ◽  
Sense And Respond ◽  
Direction Reversal

Many motile unicellular organisms have evolved specialized behaviors for detecting and responding to chemical gradients (chemotaxis) or oxygen (aerotaxis), while magnetotactic bacteria sense magnetic fields to align their direction of movement. Herein we show that Magnetospirillum magneticum (AMB-1) have the ability to sense and respond not only to the direction of magnetic fields of naturally occurring magnitude, but also to local, highly concentrated magnetic field gradients that do not occur in their natural environment. We imposed these gradients through our system integrating Helmholtz coils and permalloy (Ni80Fe20) microstructures. The AMB-1 exhibit three distinct behaviors as they approached gradients near the microstructures—unidirectional, single direction reversal, and double direction reversal. These results indicate previously unknown capabilities of the magnetic sensing systems of AMB-1.

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