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Mohammadinejad S, Faivre D, Klumpp S. Stokesian dynamics simulations of a magnetotactic bacterium. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:40. [PMID: 33759003 PMCID: PMC7987682 DOI: 10.1140/epje/s10189-021-00038-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/15/2021] [Indexed: 05/13/2023]
Abstract
The 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 ([Formula: see text]) 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.
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Affiliation(s)
- Sarah Mohammadinejad
- Institute for the Dynamics of Complex Systems, University of Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
- Department Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424, Potsdam, Germany.
- Department of Biological Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran.
| | - Damien Faivre
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14424, Potsdam, Germany
- Aix-Marseille Université, CEA, CNRS, BIAM, 13108, Saint-Paul-lez-Durance, France
| | - Stefan Klumpp
- Institute for the Dynamics of Complex Systems, University of Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany
- Department Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424, Potsdam, Germany
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Orientational dynamics of magnetotactic bacteria in Earth's magnetic field-a simulation study. J Biol Phys 2021; 47:79-93. [PMID: 33687635 DOI: 10.1007/s10867-021-09566-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 02/04/2021] [Indexed: 10/22/2022] Open
Abstract
We investigate through simulations the phenomena of magnetoreception to enable an understanding of the minimum requirements of a fail-safe mechanism, operational at the cellular level, to sense a weak magnetic field at ambient temperature in a biologically active environment. To do this, we use magnetotactic bacteria (MTB) as our model system. The magnetic field sensing ability of these bacteria is due to the presence of magnetosomes, which are internal membrane-bound organelles that contain an iron-based magnetic mineral crystal. These magnetosomes are usually found arranged in a chain aligned with the long axis of the bacterial body. This arrangement yields an overall magnetic dipole moment to the bacterial cell. To simulate this orientation process, we set up a rotational Langevin stochastic differential equation and solve it repeatedly over appropriate time steps for isolated spherical shaped MTB as well as for a more realistic model of spheroidal MTB with flagella. The orientation process appears to depend on shape parameters with spheroidal MTB showing a slower response time compared to spherical MTB. Further, our simulation also reveals that the alignment to the external magnetic field is more robust for an MTB when compared to single magnetosome. For the simulation involving magnetosomes, we include an extra torque that arises from the twisting of an attachment tether and enhance the viscosity of the surrounding medium to mimic intracellular conditions in the governing Langevin equation. The response time of alignment is found to be substantially reduced when one includes a dipole interaction term with a neighboring magnetosome and the alignment becomes less robust with increase in inter dipole distance. The alignment process can thereby be said to be very sensitively dependent on the distance between magnetosomes. Simulating the process of alignment between two neighboring magnetosomes, both in the absence and presence of an ambient magnetic field, we conclude that alignment between these dipoles at the distances typical in an MTB is highly probable and it would be the locked unit that responds to changes in the external magnetic field.
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de Melo RD, Leão P, Abreu F, Acosta-Avalos D. The swimming orientation of multicellular magnetotactic prokaryotes and uncultured magnetotactic cocci in magnetic fields similar to the geomagnetic field reveals differences in magnetotaxis between them. Antonie van Leeuwenhoek 2019; 113:197-209. [PMID: 31535336 DOI: 10.1007/s10482-019-01330-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/10/2019] [Indexed: 01/21/2023]
Abstract
Magnetotactic bacteria have intracellular chains of magnetic nanoparticles, conferring to their cellular body a magnetic moment that permits the alignment of their swimming trajectories to the geomagnetic field lines. That property is known as magnetotaxis and makes them suitable for the study of bacterial motion. The present paper studies the swimming trajectories of uncultured magnetotactic cocci and of the multicellular magnetotactic prokaryote 'Candidatus Magnetoglobus multicellularis' exposed to magnetic fields lower than 80 μT. It was assumed that the trajectories are cylindrical helixes and the axial velocity, the helix radius, the frequency and the orientation of the trajectories relative to the applied magnetic field were determined from the experimental trajectories. The results show the paramagnetic model applies well to magnetotactic cocci but not to 'Ca. M. multicellularis' in the low magnetic field regime analyzed. Magnetotactic cocci orient their trajectories as predicted by classical magnetotaxis but in general 'Ca. M. multicellularis' does not swim following the magnetic field direction, meaning that for it the inversion in the magnetic field direction represents a stimulus but the selection of the swimming direction depends on other cues or even on other mechanisms for magnetic field detection.
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Affiliation(s)
- Roger Duarte de Melo
- Centro Brasileiro de Pesquisas Fisicas - CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Pedro Leão
- Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ, 21941-902, Brazil
| | - Fernanda Abreu
- Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ, 21941-902, Brazil
| | - Daniel Acosta-Avalos
- Centro Brasileiro de Pesquisas Fisicas - CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil.
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Le Nagard L, Yu L, Rajkotwala M, Barkley S, Bazylinski DA, Hitchcock AP, Fradin C. Misalignment between the magnetic dipole moment and the cell axis in the magnetotactic bacterium Magnetospirillum magneticum AMB-1. Phys Biol 2019; 16:066008. [PMID: 31181559 DOI: 10.1088/1478-3975/ab2858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
While most quantitative studies of the motion of magnetotactic bacteria rely on the premise that the cells' magnetic dipole moment is aligned with their direction of motility, this assumption has so far rarely been challenged. Here we use phase contrast microscopy to detect the rotational diffusion of non-motile cells of Magnetospirillum magneticum AMB-1 around their magnetic moment, showing that in this species the magnetic dipole moment is, in fact, not exactly aligned with the cell body axis. From the cell rotational trajectories, we are able to infer the misalignment between cell magnetic moment and body axis with a precision of better than 1°, showing that it is, on average, 6°, and can be as high as 20°. We propose a method to correct for this misalignment, and perform a non-biased measurement of the magnetic moment of single cells based on the analysis of their orientation distribution. Using this correction, we show that magnetic moment strongly correlates with cell length. The existence of a range of misalignments between magnetic moment and cell axis in a population implies that the orientation and trajectories of magnetotactic bacteria placed in external magnetic fields is more complex than generally assumed, and might show some important cell-to-cell differences.
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Affiliation(s)
- Lucas Le Nagard
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W, Hamilton, ON L8S 4M1, Canada
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On the motion of magnetotactic bacteria: theoretical predictions and experimental observations. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2019; 48:691-700. [DOI: 10.1007/s00249-019-01394-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/29/2019] [Accepted: 08/13/2019] [Indexed: 01/08/2023]
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Acosta-Avalos D, de Figueiredo AC, Conceição CP, da Silva JJP, Aguiar KJMSP, de Lima Medeiros M, do Nascimento M, de Melo RD, Sousa SMM, de Barros HL, Alves OC, Abreu F. U-turn trajectories of magnetotactic cocci allow the study of the correlation between their magnetic moment, volume and velocity. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2019; 48:513-521. [PMID: 31203416 DOI: 10.1007/s00249-019-01375-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 05/03/2019] [Accepted: 06/09/2019] [Indexed: 06/09/2023]
Abstract
Magnetotactic bacteria are microorganisms that present intracellular chains of magnetic nanoparticles, the magnetosome chain. A challenge in the study of magnetotactic bacteria is the measurement of the magnetic moment associated with the magnetosome chain. Several techniques have been used to estimate the average magnetic moment of a population of magnetotactic bacteria, and others permit the measurement of the magnetic moment of individual bacteria. The U-turn technique allows the measurement of the individual magnetic moment and other parameters associated with the movement and magnetotaxis, such as the velocity and the orientation angle of the trajectory relative to the applied magnetic field. The aim of the present paper is to use the U-turn technique in a population of uncultured magnetotactic cocci to measure the magnetic moment, the volume, orientation angle and velocity for the same individuals. Our results showed that the magnetic moment is distributed in a log-normal distribution, with a mean value of 8.2 × 10-15 Am2 and median of 5.4 × 10-15 Am2. An estimate of the average magnetic moment using the average value of the orientation cosine produces a value similar to the median of the distribution and to the average magnetic moment obtained using transmission electron microscopy. A strong positive correlation is observed between the magnetic moment and the volume. There is no correlation between the magnetic moment and the orientation cosine and between the magnetic moment and the velocity. Those null correlations can be explained by our current understanding of magnetotaxis.
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Affiliation(s)
- Daniel Acosta-Avalos
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil.
| | - Agnes Chacor de Figueiredo
- Universidade Federal Do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil
| | - Cassia Picanço Conceição
- Universidade Federal Do Amapa (UNIFAP), Rod. Juscelino Kubitschek, KM-02, Jardim Marco Zero, Macapá, AP, 68903-419, Brazil
| | - Jayane Julia Pereira da Silva
- Universidade Federal Do Rio Grande Do Norte (UFRN), Av. Sen. Salgado Filho 3000, Campus Universitário, Lagoa Nova, Natal, RN, 59078-970, Brazil
| | | | - Marciano de Lima Medeiros
- Universidade Regional Do Cariri (URCA), Av. Leão Sampaio 107, Triângulo, Juazeiro do Norte, CE, 63041-082, Brazil
| | - Moacyr do Nascimento
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Roger Duarte de Melo
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
- Universidade Federal Do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil
| | - Saulo Machado Moreira Sousa
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Henrique Lins de Barros
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Odivaldo Cambraia Alves
- Universidade Federal Fluminense (UFF), Outeiro de São João Batista, Campus do Valonguinho, Centro, Niterói, RJ, 24020-141, Brazil
| | - Fernanda Abreu
- Instituto de Microbiologia Paulo de Goes, Universidade Federal Do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, 21941-902, Brazil
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Keim CN, Duarte de Melo R, Almeida FP, Lins de Barros HGP, Farina M, Acosta-Avalos D. Effect of applied magnetic fields on motility and magnetotaxis in the uncultured magnetotactic multicellular prokaryote 'Candidatus Magnetoglobus multicellularis'. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:465-474. [PMID: 29573371 DOI: 10.1111/1758-2229.12640] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 02/27/2018] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
Magnetotactic bacteria are found in the chemocline of aquatic environments worldwide. They produce nanoparticles of magnetic minerals arranged in chains in the cytoplasm, which enable these microorganisms to align to magnetic fields while swimming propelled by flagella. Magnetotactic bacteria are diverse phylogenetically and morphologically, including cocci, rods, vibria, spirilla and also multicellular forms, known as magnetotactic multicellular prokaryotes (MMPs). We used video-microscopy to study the motility of the uncultured MMP 'Candidatus Magnetoglobus multicellularis' under applied magnetic fields ranging from 0.9 to 32 Oersted (Oe). The bidimensional projections of the tridimensional trajectories where interpreted as plane projections of cylindrical helices and fitted as sinusoidal curves. The results showed that 'Ca. M. multicellularis' do not orient efficiently to low magnetic fields, reaching an efficiency of about 0.65 at 0.9-1.5 Oe, which are four to six times the local magnetic field. Good efficiency (0.95) is accomplished for magnetic fields ≥10 Oe. For comparison, unicellular magnetotactic microorganisms reach such efficiency at the local magnetic field. Considering that the magnetic moment of 'Ca. M. multicellularis' is sufficient for efficient alignment at the Earth's magnetic field, we suggest that misalignments are due to flagella movements, which could be driven by photo-, chemo- and/or other types of taxis.
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Affiliation(s)
- Carolina N Keim
- Instituto de Microbiologia Paulo de Góes, CCS, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro, RJ, 21941-902, Brazil
| | - Roger Duarte de Melo
- Centro Brasileiro de Pesquisas Físicas - CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Fernando P Almeida
- Instituto de Microbiologia Paulo de Góes, CCS, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro, RJ, 21941-902, Brazil
| | - Henrique G P Lins de Barros
- Centro Brasileiro de Pesquisas Físicas - CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Marcos Farina
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro, 21941-902, Brazil
| | - Daniel Acosta-Avalos
- Centro Brasileiro de Pesquisas Físicas - CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
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de Azevedo LV, de Barros HL, Keim CN, Acosta-Avalos D. Effect of light wavelength on motility and magnetic sensibility of the magnetotactic multicellular prokaryote 'Candidatus Magnetoglobus multicellularis'. Antonie van Leeuwenhoek 2013; 104:405-12. [PMID: 23828178 DOI: 10.1007/s10482-013-9964-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 06/27/2013] [Indexed: 11/29/2022]
Abstract
'Candidatus Magnetoglobus multicellularis' is a magnetotactic microorganism composed of several bacterial cells. Presently, it is the best known multicellular magnetotactic prokaryote (MMP). Recently, it has been observed that MMPs present a negative photoresponse to high intensity ultraviolet and violet-blue light. In this work, we studied the movement of 'Candidatus Magnetoglobus multicellularis' under low intensity light of different wavelengths, measuring the average velocity and the time to reorient its trajectory when the external magnetic field changes its direction (U-turn time). Our results show that the mean average velocity is higher for red light (628 nm) and lower for green light (517 nm) as compared to yellow (596 nm) and blue (469 nm) light, and the U-turn time decreased for green light illumination. The light wavelength velocity dependence can be understood as variation in flagella rotation speed, being increased by the red light and decreased by the green light relative to yellow and blue light. It is suggested that the dependence of the U-turn time on light wavelength can be considered a form of light-dependent magnetotaxis, because this time represents the magnetic sensibility of the magnetotactic microorganisms. The cellular and molecular mechanisms for this light-dependent velocity and magnetotaxis are unknown and deserve further studies to understand the biochemical interactions and the ecological roles of the different mechanisms of taxis in MMPs.
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Affiliation(s)
- Lyvia Vidinho de Azevedo
- Centro Brasileiro de Pesquisas Fisicas-CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, Brazil
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Abstract
Realization of point-to-point positioning of a magnetotactic bacterium (MTB) necessitates the application of a relatively large magnetic field gradients to decrease its velocity in the vicinity of a reference position. We investigate an alternative closed-loop control approach to position the MTB. This approach is based on the characterization of the magnetic dipole moment of the MTB and its response to a field with alternating direction. We do not only find agreement between our characterized magnetic dipole moment and previously published results, but also observe that the velocity of the MTB decreases by 37% when a field with alternating direction is applied at 85 Hz. The characterization results allow us to devise a null-space control approach which capitalizes on the redundancy of magnetic-based manipulation systems. This approach is based on two inputs. The first controls the orientation of the MTB, whereas the second generates a field with alternating direction to decrease its velocity. This control is accomplished by the redundancy of our magnetic-based manipulation system which allows for the projection of the second input onto the null-space of the magnetic force-current map of our system. A proportional–derivative control system positions the MTB at an average velocity and region of convergence of 29 μm s−1 and 20 μm, respectively, while our null-space control system achieves an average velocity and region of convergence of 15 μm s−1 and 13 μm, respectively.
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Affiliation(s)
- Islam S. M. Khalil
- MIRA–Institute for Biomedical Technology and Technical Medicine, University of Twente, The Netherlands
| | - Marc P. Pichel
- MIRA–Institute for Biomedical Technology and Technical Medicine, University of Twente, The Netherlands
| | - Leon Abelmann
- MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
| | - Sarthak Misra
- MIRA–Institute for Biomedical Technology and Technical Medicine, University of Twente, The Netherlands
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Almeida FP, Viana NB, Lins U, Farina M, Keim CN. Swimming behaviour of the multicellular magnetotactic prokaryote 'Candidatus Magnetoglobus multicellularis' under applied magnetic fields and ultraviolet light. Antonie van Leeuwenhoek 2012; 103:845-57. [PMID: 23242915 DOI: 10.1007/s10482-012-9866-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/08/2012] [Indexed: 01/26/2023]
Abstract
Magnetotactic bacteria move by rotating their flagella and concomitantly are aligned to magnetic fields because they present magnetosomes, which are intracellular organelles composed by membrane-bound magnetic crystals. This results in magnetotaxis, which is swimming along magnetic field lines. Magnetotactic bacteria are morphologically diverse, including cocci, rods, spirilla and multicellular forms known as magnetotactic multicellular prokaryotes (MMPs). 'Candidatus Magnetoglobus multicellularis' is presently the best known MMP. Here we describe the helical trajectories performed by these microorganisms as they swim forward, as well as their response to UV light. We measured the radius of the trajectory, time period and translational velocity (velocity along the helix axis), which enabled the calculation of other trajectory parameters such as pitch, tangential velocity (velocity along the helix path), angular frequency, and theta angle (the angle between the helix path and the helix axis). The data revealed that 'Ca. M. multicellularis' swims along elongated helical trajectories with diameters approaching the diameter of the microorganism. In addition, we observed that 'Ca. M. multicellularis' responds to UV laser pulses by swimming backwards, returning to forward swimming several seconds after the UV laser pulse. UV light from a fluorescence microscope showed a similar effect. Thus, phototaxis is used in addition to magnetotaxis in this microorganism.
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Affiliation(s)
- Fernando P Almeida
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro, RJ, 21941-902, Brazil
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Magnetotactic bacteria: promising biosorbents for heavy metals. Appl Microbiol Biotechnol 2012; 95:1097-104. [DOI: 10.1007/s00253-012-4245-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/13/2012] [Accepted: 06/14/2012] [Indexed: 11/27/2022]
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Newly isolated but uncultivated magnetotactic bacterium of the phylum Nitrospirae from Beijing, China. Appl Environ Microbiol 2011; 78:668-75. [PMID: 22113917 DOI: 10.1128/aem.06764-11] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Magnetotactic bacteria (MTB) in the phylum Nitrospirae synthesize up to hundreds of intracellular bullet-shaped magnetite magnetosomes. In the present study, a watermelon-shaped magnetotactic bacterium (designated MWB-1) from Lake Beihai in Beijing, China, was characterized. This uncultivated microbe was identified as a member of the phylum Nitrospirae and represents a novel phylogenetic lineage with ≥6% 16S rRNA gene sequence divergence from all currently described MTB. MWB-1 contained 200 to 300 intracellular bullet-shaped magnetite magnetosomes and showed a helical swimming trajectory under homogeneous magnetic fields; its magnetotactic velocity decreased with increasing field strength, and vice versa. A robust phylogenetic framework for MWB-1 and all currently known MTB in the phylum Nitrospirae was constructed utilizing maximum-likelihood and Bayesian algorithms, which yielded strong evidence that the Nitrospirae MTB could be divided into four well-supported groups. Considering its population densities in sediment and its high numbers of magnetosomes, MWB-1 was estimated to account for more than 10% of the natural remanent magnetization of the surface sediment. Taken together, the results of this study suggest that MTB in the phylum Nitrospirae are more diverse than previously realized and can make important contributions to the sedimentary magnetization in particular environments.
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A cybernetic perspective on food protection in rats: simple rules can generate complex and adaptable behaviour. Anim Behav 2011. [DOI: 10.1016/j.anbehav.2011.06.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lefèvre CT, Frankel RB, Abreu F, Lins U, Bazylinski DA. Culture-independent characterization of a novel, uncultivated magnetotactic member of the Nitrospirae phylum. Environ Microbiol 2010; 13:538-49. [PMID: 20977572 DOI: 10.1111/j.1462-2920.2010.02361.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A magnetotactic bacterium, designated strain LO-1, of the Nitrospirae phylum was detected and concentrated from a number of freshwater and slightly brackish aquatic environments in southern Nevada. The closest phylogenetic relative to LO-1 is Candidatus Magnetobacterium bavaricum based on a 91.2% identity in their 16S rRNA gene sequence. Chemical and cell profiles of a microcosm containing water and sediment show that cells of strain LO-1 are confined to the oxic-anoxic interface and the upper regions of the anaerobic zone which in this case, occurred in the sediment. This microorganism is relatively large, ovoid in morphology and usually biomineralizes three braid-like bundles of multiple chains of bullet-shaped magnetosomes that appeared to be enclosed in a magnetosome membrane. Cells of LO-1 had an unusual three-layered unit membrane cell wall and contained several types of inclusions, some of which are sulfur-rich. Strain LO-1 is motile by means of a single bundle of sheathed flagella and exhibits the typical 'wobbling' motility and helical swimming ('flight') path of the magnetotactic cocci. This study and reports from others suggest that LO-1-like organisms are widespread in sediments of freshwater to brackish natural aquatic environments.
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Affiliation(s)
- Christopher T Lefèvre
- School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, NV 89154-4004, USA
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Reduced efficiency of magnetotaxis in magnetotactic coccoid bacteria in higher than geomagnetic fields. Biophys J 2009; 97:986-91. [PMID: 19686645 DOI: 10.1016/j.bpj.2009.06.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 06/09/2009] [Accepted: 06/11/2009] [Indexed: 11/21/2022] Open
Abstract
Magnetotactic bacteria are microorganisms that orient and migrate along magnetic field lines. The classical model of polar magnetotaxis predicts that the field-parallel migration velocity of magnetotactic bacteria increases monotonically with the strength of an applied magnetic field. We here test this model experimentally on magnetotactic coccoid bacteria that swim along helical trajectories. It turns out that the contribution of the field-parallel migration velocity decreases with increasing field strength from 0.1 to 1.5 mT. This unexpected observation can be explained and reproduced in a mathematical model under the assumption that the magnetosome chain is inclined with respect to the flagellar propulsion axis. The magnetic disadvantage, however, becomes apparent only in stronger than geomagnetic fields, which suggests that magnetotaxis is optimized under geomagnetic field conditions. It is therefore not beneficial for these bacteria to increase their intracellular magnetic dipole moment beyond the value needed to overcome Brownian motion in geomagnetic field conditions.
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Magnetic properties of the microorganism Candidatus Magnetoglobus multicellularis. Naturwissenschaften 2009; 96:685-90. [DOI: 10.1007/s00114-009-0520-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 02/02/2009] [Accepted: 02/18/2009] [Indexed: 10/21/2022]
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Silva KT, Abreu F, Almeida FP, Keim CN, Farina M, Lins U. Flagellar apparatus of south-seeking many-celled magnetotactic prokaryotes. Microsc Res Tech 2007; 70:10-7. [PMID: 17019700 DOI: 10.1002/jemt.20380] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magnetotactic bacteria orient and migrate along geomagnetic field lines. Each cell contains membrane-enclosed, nano-scale, iron-mineral particles called magnetosomes that cause alignment of the cell in the geomagnetic field as the bacteria swim propelled by flagella. In this work we studied the ultrastructure of the flagellar apparatus in many-celled magnetotactic prokaryotes (MMP) that consist of several Gram-negative cells arranged radially around an acellular compartment. Flagella covered the organism surface, and were observed exclusively at the portion of each cell that faced the environment. The flagella were helical tubes never as long as a complete turn of the helix. Flagellar filaments varied in length from 0.9 to 3.8 micro m (average 2.4 +/- 0.5 micro m, n = 150) and in width from 12.0 to 19.5 nm (average 15.9 +/- 1.4 nm, n = 52), which is different from previous reports for similar microorganisms. At the base of the flagella, a curved hook structure slightly thicker than the flagellar filaments was observed. In freeze-fractured samples, macromolecular complexes about 50 nm in diameter, which possibly corresponded to part of the flagella basal body, were observed in both the P-face of the cytoplasmic membrane and the E-face of the outer membrane. Transmission electron microscopy showed that magnetosomes occurred in planar groups in the cytoplasm close and parallel to the organism surface. A striated structure, which could be involved in maintaining magnetosomes fixed in the cell, was usually observed running along magnetosome chains. The coordinated movement of the MMP depends on the interaction between the flagella of each cell with the flagella of adjacent cells of the microorganism.
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Affiliation(s)
- Karen Tavares Silva
- Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, Rio de Janeiro, Brazil
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Lins U, McCartney MR, Farina M, Frankel RB, Buseck PR. Crystal habits and magnetic microstructures of magnetosomes in coccoid magnetotactic bacteria. AN ACAD BRAS CIENC 2007; 78:463-74. [PMID: 16936936 DOI: 10.1590/s0001-37652006000300007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Accepted: 02/17/2006] [Indexed: 11/21/2022] Open
Abstract
We report on the application of off-axis electron holography and high-resolution TEM to study the crystal habits of magnetosomes and magnetic microstructure in two coccoid morphotypes of magnetotactic bacteria collected from a brackish lagoon at Itaipu, Brazil. Itaipu-1, the larger coccoid organism, contains two separated chains of unusually large magnetosomes; the magnetosome crystals have roughly square projections, lengths up to 250 nm and are slightly elongated along [111] (width/length ratio of about 0.9). Itaipu-3 magnetosome crystals have lengths up to 120 nm, greater elongation along [111] (width/length approximately 0.6), and prominent corner facets. The results show that Itaipu-1 and Itaipu-3 magnetosome crystal habits are related, differing only in the relative sizes of their crystal facets. In both cases, the crystals are aligned with their [111] elongation axes parallel to the chain direction. In Itaipu-1, but not Itaipu-3, crystallographic positioning perpendicular to [111] of successive crystals in the magnetosome chain appears to be under biological control. Whereas the large magnetosomes in Itaipu-1 are metastable, single-magnetic domains, magnetosomes in Itaipu-3 are permanent, single-magnetic domains, as in most magnetotactic bacteria.
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Affiliation(s)
- Ulysses Lins
- Instituto de Microbiologia Professor Paulo de Góes, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
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Winklhofer M, Abraçado LG, Davila AF, Keim CN, Lins de Barros HGP. Magnetic optimization in a multicellular magnetotactic organism. Biophys J 2006; 92:661-70. [PMID: 17071652 PMCID: PMC1751416 DOI: 10.1529/biophysj.106.093823] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Unicellular magnetotactic prokaryotes, which typically carry a natural remanent magnetic moment equal to the saturation magnetic moment, are the prime example of magnetically optimized organisms. We here report magnetic measurements on a multicellular magnetotactic prokaryote (MMP) consisting of 17 undifferentiated cells (mean from 148 MMPs) with chains of ferrimagnetic particles in each cell. To test if the chain polarities of each cell contribute coherently to the total magnetic moment of the MMP, we used a highly sensitive magnetization measurement technique (1 fAm(2)) that enabled us to determine the degree of magnetic optimization (DMO) of individual MMPs in vivo. We obtained DMO values consistently above 80%. Numerical modeling shows that the probability of reaching a DMO > 80% would be as low as 0.017 for 17 randomly oriented magnetic dipoles. We simulated different scenarios to test whether high DMOs are attainable by aggregation or self-organization of individual magnetic cells. None of the scenarios investigated is likely to yield consistently high DMOs in each generation of MMPs. The observed high DMO values require strong Darwinian selection and a sophisticated reproduction mechanism. We suggest a multicellular life cycle as the most plausible scenario for transmitting the high DMO from one generation to the next.
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Affiliation(s)
- Michael Winklhofer
- Department of Earth and Environmental Science, Ludwig-Maximilians-University of Munich, Munich, Germany.
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Cēbers A, Ozols M. Dynamics of an active magnetic particle in a rotating magnetic field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:021505. [PMID: 16605340 DOI: 10.1103/physreve.73.021505] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 10/21/2005] [Indexed: 05/08/2023]
Abstract
The motion of an active (self-propelling) particle with a permanent magnetic moment under the action of a rotating magnetic field is considered. We show that below a critical frequency of the external field the trajectory of a particle is a circle. For frequencies slightly above the critical point the particle moves on an approximately circular trajectory and from time to time jumps to another region of space. Symmetry of the particle trajectory depends on the commensurability of the field period and the period of the orientational motion of the particle. We also show how our results can be used to study the properties of naturally occurring active magnetic particles, so-called magnetotactic bacteria.
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Affiliation(s)
- A Cēbers
- Institute of Physics, University of Latvia, Salaspils-1, LV-2169, Latvia.
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Chemla YR, Grossman HL, Lee TS, Clarke J, Adamkiewicz M, Buchanan BB. A new study of bacterial motion: superconducting quantum interference device microscopy of magnetotactic bacteria. Biophys J 1999; 76:3323-30. [PMID: 10354458 PMCID: PMC1300302 DOI: 10.1016/s0006-3495(99)77485-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The recently developed "microscope" based on a high-Tc dc SQUID (superconducting quantum interference device) is used to detect the magnetic fields produced by the motion of magnetotactic bacteria, which have permanent dipole moments. The bacteria, in growth medium at room temperature, can be brought to within 15 micron of a SQUID at liquid nitrogen temperature. Measurements are performed on both motile and nonmotile bacteria. In the nonmotile case, we obtain the power spectrum of the magnetic field noise produced by the rotational Brownian motion of the ensemble of bacteria. Furthermore, we measure the time-dependent field produced by the ensemble in response to an applied uniform magnetic field. In the motile case, we obtain the magnetic field power spectra produced by the swimming bacteria. Combined, these measurements determine the average rotational drag coefficient, magnetic moment, and the frequency and amplitude of the vibrational and rotational modes of the bacteria in a unified set of measurements. In addition, the microscope can easily resolve the motion of a single bacterium. This technique can be extended to any cell to which a magnetic tag can be attached.
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Affiliation(s)
- Y R Chemla
- Department of Physics, University of California, Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory, California 94720, USA.
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