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Sarimov RM, Serov DA, Gudkov SV. Hypomagnetic Conditions and Their Biological Action (Review). BIOLOGY 2023; 12:1513. [PMID: 38132339 PMCID: PMC10740674 DOI: 10.3390/biology12121513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/30/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023]
Abstract
The geomagnetic field plays an important role in the existence of life on Earth. The study of the biological effects of (hypomagnetic conditions) HMC is an important task in magnetobiology. The fundamental importance is expanding and clarifying knowledge about the mechanisms of magnetic field interaction with living systems. The applied significance is improving the training of astronauts for long-term space expeditions. This review describes the effects of HMC on animals and plants, manifested at the cellular and organismal levels. General information is given about the probable mechanisms of HMC and geomagnetic field action on living systems. The main experimental approaches are described. We attempted to systematize quantitative data from various studies and identify general dependencies of the magnetobiology effects' value on HMC characteristics (induction, exposure duration) and the biological parameter under study. The most pronounced effects were found at the cellular level compared to the organismal level. Gene expression and protein activity appeared to be the most sensitive to HMC among the molecular cellular processes. The nervous system was found to be the most sensitive in the case of the organism level. The review may be of interest to biologists, physicians, physicists, and specialists in interdisciplinary fields.
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Affiliation(s)
| | | | - Sergey V. Gudkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilove St. 38, 119991 Moscow, Russia; (R.M.S.); (D.A.S.)
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2
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Mao X, Egli R, Liu X, Zhao L. Magnetotactic advantage in stable sediment by long-term observations of magnetotactic bacteria in Earth’s field, zero field and alternating field. PLoS One 2022; 17:e0263593. [PMID: 35202421 PMCID: PMC8870540 DOI: 10.1371/journal.pone.0263593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 01/21/2022] [Indexed: 12/02/2022] Open
Abstract
Magnetotactic bacteria (MTB) rely on magnetotaxis to effectively reach their preferred living habitats, whereas experimental investigation of magnetotactic advantage in stable sediment is currently lacking. We studied two wild type MTB (cocci and rod-shaped M. bavaricum) in sedimentary environment under exposure to geomagnetic field in the laboratory, zero field and an alternating field whose polarity was switched every 24 hours. The mean concentration of M. bavaricum dropped by ~50% during 6 months in zero field, with no clear temporal trend suggesting an extinction. Cell numbers recovered to initial values within ~1.5 months after the Earth’s field was reset. Cocci displayed a larger temporal variability with no evident population changes in zero field. The alternating field experiment produced a moderate decrease of M. bavaricum concentrations and nearby extinction of cocci, confirming the active role of magnetotaxis in sediment and might point to a different magnetotactic mechanism for M. bavaricum which possibly benefited them to survive field reversals in geological periods. Our findings provide a first quantification of magnetotaxis advantage in sedimentary environment.
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Affiliation(s)
- Xuegang Mao
- College of Geographical Sciences, Fujian Normal University, Fuzhou, China
- Institute of Geography, Fujian Normal University, Fuzhou, China
- * E-mail:
| | - Ramon Egli
- Central institute for Meteorology and Geodynamics, Vienna, Austria
| | - Xiuming Liu
- College of Geographical Sciences, Fujian Normal University, Fuzhou, China
- Institute of Geography, Fujian Normal University, Fuzhou, China
- Department of Earth and Environmental Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Lijuan Zhao
- College of Geographical Sciences, Fujian Normal University, Fuzhou, China
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3
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A Theoretical Analysis of Magnetic Particle Alignment in External Magnetic Fields Affected by Viscosity and Brownian Motion. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11209651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The interaction of an external magnetic field with magnetic objects affects their response and is a fundamental property for many biomedical applications, including magnetic resonance and particle imaging, electromagnetic hyperthermia, and magnetic targeting and separation. Magnetic alignment and relaxation are widely studied in the context of these applications. In this study, we theoretically investigate the alignment dynamics of a rotational magnetic particle as an inverse process to Brownian relaxation. The selected external magnetic flux density ranges from 5μT to 5T. We found that the viscous torque for arbitrary rotating particles with a history term due to the inertia and friction of the surrounding ambient water has a significant effect in strong magnetic fields (range 1–5T). In this range, oscillatory behavior due to the inertial torque of the particle also occurs, and the stochastic Brownian torque diminishes. In contrast, for weak fields (range 5–50μT), the history term of the viscous torque and the inertial torque can be neglected, and the stochastic Brownian torque induced by random collisions of the surrounding fluid molecules becomes dominant. These results contribute to a better understanding of the molecular mechanisms of magnetic particle alignment in external magnetic fields and have important implications in a variety of biomedical applications.
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Gudkov SV, Burmistrov DE, Serov DA, Rebezov MB, Semenova AA, Lisitsyn AB. Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties? ANTIBIOTICS (BASEL, SWITZERLAND) 2021; 10:antibiotics10070884. [PMID: 34356805 DOI: 10.3389/fphy.2021.641481] [Citation(s) in RCA: 135] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/12/2021] [Accepted: 07/18/2021] [Indexed: 05/22/2023]
Abstract
The use of metal oxide nanoparticles is one of the promising ways for overcoming antibiotic resistance in bacteria. Iron oxide nanoparticles (IONPs) have found wide applications in different fields of biomedicine. Several studies have suggested using the antimicrobial potential of IONPs. Iron is one of the key microelements and plays an important role in the function of living systems of different hierarchies. Iron abundance and its physiological functions bring into question the ability of iron compounds at the same concentrations, on the one hand, to inhibit the microbial growth and, on the other hand, to positively affect mammalian cells. At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi. Several studies have established that IONPs have a low toxicity to eukaryotic cells. It gives hope that IONPs can be considered potential antimicrobial agents of the new generation that combine antimicrobial action and high biocompatibility with the human body. This review is intended to inform readers about the available data on the antimicrobial properties of IONPs, a range of susceptible bacteria, mechanisms of the antibacterial action, dependence of the antibacterial action of IONPs on the method for synthesis, and the biocompatibility of IONPs with eukaryotic cells and tissues.
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Affiliation(s)
- Sergey V Gudkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Dmitriy E Burmistrov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Dmitriy A Serov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Maksim B Rebezov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
- V.M. Gorbatov Federal Research Center for Food Systems of the Russian Academy of Sciences, 109316 Moscow, Russia
| | - Anastasia A Semenova
- V.M. Gorbatov Federal Research Center for Food Systems of the Russian Academy of Sciences, 109316 Moscow, Russia
| | - Andrey B Lisitsyn
- V.M. Gorbatov Federal Research Center for Food Systems of the Russian Academy of Sciences, 109316 Moscow, Russia
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Gudkov SV, Burmistrov DE, Serov DA, Rebezov MB, Semenova AA, Lisitsyn AB. Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties? Antibiotics (Basel) 2021; 10:884. [PMID: 34356805 PMCID: PMC8300809 DOI: 10.3390/antibiotics10070884] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/12/2021] [Accepted: 07/18/2021] [Indexed: 02/06/2023] Open
Abstract
The use of metal oxide nanoparticles is one of the promising ways for overcoming antibiotic resistance in bacteria. Iron oxide nanoparticles (IONPs) have found wide applications in different fields of biomedicine. Several studies have suggested using the antimicrobial potential of IONPs. Iron is one of the key microelements and plays an important role in the function of living systems of different hierarchies. Iron abundance and its physiological functions bring into question the ability of iron compounds at the same concentrations, on the one hand, to inhibit the microbial growth and, on the other hand, to positively affect mammalian cells. At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi. Several studies have established that IONPs have a low toxicity to eukaryotic cells. It gives hope that IONPs can be considered potential antimicrobial agents of the new generation that combine antimicrobial action and high biocompatibility with the human body. This review is intended to inform readers about the available data on the antimicrobial properties of IONPs, a range of susceptible bacteria, mechanisms of the antibacterial action, dependence of the antibacterial action of IONPs on the method for synthesis, and the biocompatibility of IONPs with eukaryotic cells and tissues.
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Affiliation(s)
- Sergey V. Gudkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; (D.E.B.); (D.A.S.); (M.B.R.)
| | - Dmitriy E. Burmistrov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; (D.E.B.); (D.A.S.); (M.B.R.)
| | - Dmitriy A. Serov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; (D.E.B.); (D.A.S.); (M.B.R.)
| | - Maksim B. Rebezov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; (D.E.B.); (D.A.S.); (M.B.R.)
- V.M. Gorbatov Federal Research Center for Food Systems of the Russian Academy of Sciences, 109316 Moscow, Russia; (A.A.S.); (A.B.L.)
| | - Anastasia A. Semenova
- V.M. Gorbatov Federal Research Center for Food Systems of the Russian Academy of Sciences, 109316 Moscow, Russia; (A.A.S.); (A.B.L.)
| | - Andrey B. Lisitsyn
- V.M. Gorbatov Federal Research Center for Food Systems of the Russian Academy of Sciences, 109316 Moscow, Russia; (A.A.S.); (A.B.L.)
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Min JJ, Thi-Quynh Duong M, Ramar T, You SH, Kang SR. Theranostic Approaches Using Live Bacteria. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00056-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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A Sensitive Magnetic Arsenite-Specific Biosensor Hosted in Magnetotactic Bacteria. Appl Environ Microbiol 2020; 86:AEM.00803-20. [PMID: 32385084 DOI: 10.1128/aem.00803-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 05/01/2020] [Indexed: 01/22/2023] Open
Abstract
According to the World Health Organization, arsenic is the water contaminant that affects the largest number of people worldwide. To limit its impact on the population, inexpensive, quick, and easy-to-use systems of detection are required. One promising solution could be the use of whole-cell biosensors, which have been extensively studied and could meet all these criteria even though they often lack sensitivity. Here, we investigated the benefit of using magnetotactic bacteria as cellular chassis to design and build sensitive magnetic bacterial biosensors. Promoters potentially inducible by arsenic were first identified in silico within the genomes of two magnetotactic bacteria strains, Magnetospirillum magneticum AMB-1 and Magnetospirillum gryphiswaldense MSR-1. The ArsR-dependent regulation was confirmed by reverse transcription-PCR experiments. Biosensors built by transcriptional fusion between the arsenic-inducible promoters and the bacterial luciferase luxCDABE operon gave an element-specific response in 30 min with an arsenite detection limit of 0.5 μM. After magnetic concentration, we improved the sensitivity of the biosensor by a factor of 50 to reach 10 nM, more than 1 order of magnitude below the recommended guidelines for arsenic in drinking water (0.13 μM). Finally, we demonstrated the successful preservation of the magnetic bacterium biosensors by freeze-drying.IMPORTANCE Whole-cell biosensors based on reporter genes can be designed for heavy metal detection but often require the optimization of their sensitivity and specific adaptations for practical use in the field. Magnetotactic bacteria as cellular hosts for biosensors are interesting models, as their intrinsic magnetism permits them to be easily concentrated and entrapped to increase the arsenic-response signal. This paves the way for the development of sensitive and immobilized whole-cell biosensors tailored for use in the field.
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8
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Quantifying the Benefit of a Dedicated "Magnetoskeleton" in Bacterial Magnetotaxis by Live-Cell Motility Tracking and Soft Agar Swimming Assay. Appl Environ Microbiol 2020; 86:AEM.01976-19. [PMID: 31732570 DOI: 10.1128/aem.01976-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/08/2019] [Indexed: 12/20/2022] Open
Abstract
The alphaproteobacterium Magnetospirillum gryphiswaldense has the intriguing ability to navigate within magnetic fields, a behavior named magnetotaxis, governed by the formation of magnetosomes, intracellular membrane-enveloped crystals of magnetite. Magnetosomes are aligned in chains along the cell's motility axis by a dedicated multipart cytoskeleton ("magnetoskeleton"); however, precise estimates of its significance for magnetotaxis have not been reported. Here, we estimated the alignment of strains deficient in various magnetoskeletal constituents by live-cell motility tracking within defined magnetic fields ranging from 50 μT (reflecting the geomagnetic field) up to 400 μT. Motility tracking revealed that ΔmamY and ΔmamK strains (which assemble mispositioned and fragmented chains, respectively) are partially impaired in magnetotaxis, with approximately equal contributions of both proteins. This impairment was reflected by a required magnetic field strength of 200 μT to achieve a similar degree of alignment as for the wild-type strain in a 50-μT magnetic field. In contrast, the ΔmamJ strain, which predominantly forms clusters of magnetosomes, was only weakly aligned under any of the tested field conditions and could barely be distinguished from a nonmagnetic mutant. Most findings were corroborated by a soft agar swimming assay to analyze magnetotaxis based on the degree of distortion of swim halos formed in magnetic fields. Motility tracking further revealed that swimming speeds of M. gryphiswaldense are highest within the field strength equaling the geomagnetic field. In conclusion, magnetic properties and intracellular positioning of magnetosomes by a dedicated magnetoskeleton are required and optimized for bacterial magnetotaxis and most efficient locomotion within the geomagnetic field.IMPORTANCE In Magnetospirillum gryphiswaldense, magnetosomes are aligned in quasi-linear chains in a helical cell by a complex cytoskeletal network, including the actin-like MamK and adapter MamJ for magnetosome chain concatenation and segregation and MamY to position magnetosome chains along the shortest cellular axis of motility. Magnetosome chain positioning is assumed to be required for efficient magnetic navigation; however, the significance and contribution of all key constituents have not been quantified within defined and weak magnetic fields reflecting the geomagnetic field. Employing two different motility-based methods to consider the flagellum-mediated propulsion of cells, we depict individual benefits of all magnetoskeletal constituents for magnetotaxis. Whereas lack of mamJ resulted almost in an inability to align cells in weak magnetic fields, an approximately 4-fold-increased magnetic field strength was required to compensate for the loss of mamK or mamY In summary, the magnetoskeleton and optimal positioning of magnetosome chains are required for efficient magnetotaxis.
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9
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Gurung JP, Gel M, Baker MAB. Microfluidic techniques for separation of bacterial cells via taxis. MICROBIAL CELL (GRAZ, AUSTRIA) 2020; 7:66-79. [PMID: 32161767 PMCID: PMC7052948 DOI: 10.15698/mic2020.03.710] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/24/2019] [Accepted: 01/10/2020] [Indexed: 12/22/2022]
Abstract
The microbial environment is typically within a fluid and the key processes happen at the microscopic scale where viscosity dominates over inertial forces. Microfluidic tools are thus well suited to study microbial motility because they offer precise control of spatial structures and are ideal for the generation of laminar fluid flows with low Reynolds numbers at microbial lengthscales. These tools have been used in combination with microscopy platforms to visualise and study various microbial taxes. These include establishing concentration and temperature gradients to influence motility via chemotaxis and thermotaxis, or controlling the surrounding microenvironment to influence rheotaxis, magnetotaxis, and phototaxis. Improvements in microfluidic technology have allowed fine separation of cells based on subtle differences in motility traits and have applications in synthetic biology, directed evolution, and applied medical microbiology.
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Affiliation(s)
- Jyoti P. Gurung
- School of Biotechnology and Biomolecular Science, UNSW Sydney
| | - Murat Gel
- CSIRO Manufacturing, Clayton
- CSIRO Future Science Platform for Synthetic Biology
| | - Matthew A. B. Baker
- School of Biotechnology and Biomolecular Science, UNSW Sydney
- CSIRO Future Science Platform for Synthetic Biology
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10
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Codutti A, Bente K, Faivre D, Klumpp S. Chemotaxis in external fields: Simulations for active magnetic biological matter. PLoS Comput Biol 2019; 15:e1007548. [PMID: 31856155 PMCID: PMC6941824 DOI: 10.1371/journal.pcbi.1007548] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 01/03/2020] [Accepted: 11/14/2019] [Indexed: 12/29/2022] Open
Abstract
The movement of microswimmers is often described by active Brownian particle models. Here we introduce a variant of these models with several internal states of the swimmer to describe stochastic strategies for directional swimming such as run and tumble or run and reverse that are used by microorganisms for chemotaxis. The model includes a mechanism to generate a directional bias for chemotaxis and interactions with external fields (e.g., gravity, magnetic field, fluid flow) that impose forces or torques on the swimmer. We show how this modified model can be applied to various scenarios: First, the run and tumble motion of E. coli is used to establish a paradigm for chemotaxis and investigate how it is affected by external forces. Then, we study magneto-aerotaxis in magnetotactic bacteria, which is biased not only by an oxygen gradient towards a preferred concentration, but also by magnetic fields, which exert a torque on an intracellular chain of magnets. We study the competition of magnetic alignment with active reorientation and show that the magnetic orientation can improve chemotaxis and thereby provide an advantage to the bacteria, even at rather large inclination angles of the magnetic field relative to the oxygen gradient, a case reminiscent of what is expected for the bacteria at or close to the equator. The highest gain in chemotactic velocity is obtained for run and tumble with a magnetic field parallel to the gradient, but in general a mechanism for reverse motion is necessary to swim against the magnetic field and a run and reverse strategy is more advantageous in the presence of a magnetic torque. This finding is consistent with observations that the dominant mode of directional changes in magnetotactic bacteria is reversal rather than tumbles. Moreover, it provides guidance for the design of future magnetic biohybrid swimmers. In this paper, we propose a modified Active Brownian particle model to describe bacterial swimming behavior under the influence of external forces and torques, in particular of a magnetic torque. This type of interaction is particularly important for magnetic biohybrids (i.e. motile bacteria coupled to a synthetic magnetic component) and for magnetotactic bacteria (i.e. bacteria with a natural intracellular magnetic chain), which perform chemotaxis to swim along chemical gradients, but are also directed by an external magnetic field. The model allows us to investigate the benefits and disadvantages of such coupling between two different directionality mechanisms. In particular we show that the magnetic torque can speed chemotaxis up in some conditions, while it can hinder it in other cases. In addition to an understanding of the swimming strategies of naturally magnetotactic organisms, the results may guide the design of future biomedical devices.
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Affiliation(s)
- Agnese Codutti
- Department Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
- Department Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
- University of Potsdam, Institute of Physics and Astronomy, Potsdam, Germany
- * E-mail: (AC); (SK)
| | - Klaas Bente
- Department Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Damien Faivre
- Department Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
- Aix Marseille University, CNRS, CEA, BIAM, 13108 Saint Paul lez Durance, France
| | - Stefan Klumpp
- Department Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
- Institute for the Dynamics of Complex Systems, University of Göttingen, Göttingen, Germany
- * E-mail: (AC); (SK)
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Pierce CJ, Osborne E, Mumper E, Lower BH, Lower SK, Sooryakumar R. Thrust and Power Output of the Bacterial Flagellar Motor: A Micromagnetic Tweezers Approach. Biophys J 2019; 117:1250-1257. [PMID: 31540710 DOI: 10.1016/j.bpj.2019.08.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/27/2019] [Accepted: 08/30/2019] [Indexed: 02/03/2023] Open
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.
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Affiliation(s)
| | - Emily Osborne
- Department of Physics, The Ohio State University, Columbus, Ohio
| | - Eric Mumper
- School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio
| | - Brian H Lower
- School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio
| | - Steven K Lower
- School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio; School of Earth Sciences, The Ohio State University, Columbus, Ohio; Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio
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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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13
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Dieudonné A, Pignol D, Prévéral S. Magnetosomes: biogenic iron nanoparticles produced by environmental bacteria. Appl Microbiol Biotechnol 2019; 103:3637-3649. [PMID: 30903215 DOI: 10.1007/s00253-019-09728-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 02/22/2019] [Accepted: 02/25/2019] [Indexed: 01/10/2023]
Abstract
The scientific community's interest in magnetotactic bacteria has increased substantially in recent decades. These prokaryotes have the particularity of synthesizing nanomagnets, called magnetosomes. The majority of research is based on several scientific questions. Where do magnetotactic bacteria live, what are their characteristics, and why are they magnetic? What are the molecular phenomena of magnetosome biomineralization and what are the physical characteristics of magnetosomes? In addition to scientific curiosity to better understand these stunning organisms, there are biotechnological opportunities to consider. Magnetotactic bacteria, as well as magnetosomes, are used in medical applications, for example cancer treatment, or in environmental ones, for example bioremediation. In this mini-review, we investigated all the aspects mentioned above and summarized the currently available knowledge.
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Affiliation(s)
- Anissa Dieudonné
- UMR 7265, Aix Marseille Univ, CEA, CNRS, BIAM, LBC, Saint Paul-Lez-Durance, France
| | - David Pignol
- UMR 7265, Aix Marseille Univ, CEA, CNRS, BIAM, LBC, Saint Paul-Lez-Durance, France
| | - Sandra Prévéral
- UMR 7265, Aix Marseille Univ, CEA, CNRS, BIAM, LBC, Saint Paul-Lez-Durance, France.
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Marcuello C, Chambel L, Rodrigues MS, Ferreira LP, Cruz MM. Magnetotactic Bacteria: Magnetism Beyond Magnetosomes. IEEE Trans Nanobioscience 2018; 17:555-559. [PMID: 30371384 DOI: 10.1109/tnb.2018.2878085] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Magnetotactic bacteria are a group of organisms deeply studied in the last years due to their interesting magnetic behavior and potential applications in nanometrology, hyperthermia, and biosensor devices. One intrinsic common characteristic is the presence, inside the bacteria, of magnetic nanoparticles called magnetosomes. The role of magnetosomes as bacterial tools to orient the bacteria and find new habitats is universally accepted, but the way they develop still is not fully understood. A strain of Magnetospirillum magnetotacticum was grown and investigated at the nanoscale using transmission electron microscopy and atomic/magnetic force microscopy techniques. Magnetosomes were observed as well as long filaments with magnetic response that could be associated to the actin-like filaments being crucial to allow the nanoparticles orientation and magnetosomes formation. To the best of our knowledge, this paper is the first to visualize these reproducible long-range size magnetic crystalline structures.
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15
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Sun YS. Studying Electrotaxis in Microfluidic Devices. SENSORS (BASEL, SWITZERLAND) 2017; 17:E2048. [PMID: 28880251 PMCID: PMC5621068 DOI: 10.3390/s17092048] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/05/2017] [Accepted: 09/05/2017] [Indexed: 12/11/2022]
Abstract
Collective cell migration is important in various physiological processes such as morphogenesis, cancer metastasis and cell regeneration. Such migration can be induced and guided by different chemical and physical cues. Electrotaxis, referring to the directional migration of adherent cells under stimulus of electric fields, is believed to be highly involved in the wound-healing process. Electrotactic experiments are conventionally conducted in Petri dishes or cover glasses wherein cells are cultured and electric fields are applied. However, these devices suffer from evaporation of the culture medium, non-uniformity of electric fields and low throughput. To overcome these drawbacks, micro-fabricated devices composed of micro-channels and fluidic components have lately been applied to electrotactic studies. Microfluidic devices are capable of providing cells with a precise micro-environment including pH, nutrition, temperature and various stimuli. Therefore, with the advantages of reduced cell/reagent consumption, reduced Joule heating and uniform and precise electric fields, microfluidic chips are perfect platforms for observing cell migration under applied electric fields. In this paper, I review recent developments in designing and fabricating microfluidic devices for studying electrotaxis, aiming to provide critical updates in this rapidly-growing, interdisciplinary field.
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Affiliation(s)
- Yung-Shin Sun
- Department of Physics, Fu-Jen Catholic University, New Taipei City 24205, Taiwan.
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16
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Lenders JJM, Mirabello G, Sommerdijk NAJM. Bioinspired magnetite synthesis via solid precursor phases. Chem Sci 2016; 7:5624-5634. [PMID: 30034699 PMCID: PMC6021960 DOI: 10.1039/c6sc00523c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 06/12/2016] [Indexed: 12/15/2022] Open
Abstract
Living organisms often exploit solid but poorly ordered mineral phases as precursors in the biomineralization of their inorganic body parts.
Living organisms often exploit solid but poorly ordered mineral phases as precursors in the biomineralization of their inorganic body parts. Generally speaking, such precursor-based approaches allow the organisms – without the need of high supersaturation levels – to accumulate significant quantities of mineral material at the desired place and time, where they can be molded and crystallized into the right morphology and structure. This strategy is also of interest in the field of bioinspired materials science, as it potentially enables the bottom-up creation of novel materials with equal or improved functionality as compared to Nature, in water and at ambient temperatures. Also for the biomineralization of magnetite (Fe3O4) such a strategy has been reported: ferrihydrite, a poorly crystalline iron oxide, has been identified as a precursor for the final magnetite phase in the magnetosomes of magnetotactic bacteria as well as in the outer layers of chiton teeth. In this perspective, we discuss the efforts of us and others to understand and tune the nucleation and growth of magnetite crystals to date, in aqueous, room-temperature syntheses and employing different solid precursor phases. The various examples demonstrate the importance of the precursor approach in controlling the different properties of magnetite nanoparticles.
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Affiliation(s)
- Jos J M Lenders
- Laboratory of Materials and Interface Chemistry , Centre for Multiscale Electron Microscopy , Department of Chemical Engineering and Chemistry , Institute for Complex Molecular Systems , Eindhoven University of Technology , PO box 513 , 5600 MB Eindhoven , The Netherlands .
| | - Giulia Mirabello
- Laboratory of Materials and Interface Chemistry , Centre for Multiscale Electron Microscopy , Department of Chemical Engineering and Chemistry , Institute for Complex Molecular Systems , Eindhoven University of Technology , PO box 513 , 5600 MB Eindhoven , The Netherlands .
| | - Nico A J M Sommerdijk
- Laboratory of Materials and Interface Chemistry , Centre for Multiscale Electron Microscopy , Department of Chemical Engineering and Chemistry , Institute for Complex Molecular Systems , Eindhoven University of Technology , PO box 513 , 5600 MB Eindhoven , The Netherlands .
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17
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Loehr J, Pfeiffer D, Schüler D, Fischer TM. Magnetic guidance of the magnetotactic bacterium Magnetospirillum gryphiswaldense. SOFT MATTER 2016; 12:3631-3635. [PMID: 26972517 DOI: 10.1039/c6sm00384b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Magnetospirillum gryphiswaldense is a magnetotactic bacterium with a permanent magnetic moment capable of swimming using two bipolarly located flagella. In their natural environment these bacteria swim along the field lines of the homogeneous geomagnetic field in a typical run and reversal pattern and thereby create non-differentiable trajectories with sharp edges. In the current work we nevertheless achieve stable guidance along curved lines of mechanical instability by using a heterogeneous magnetic field of a garnet film. The successful guidance of the bacteria depends on the right balance between motility and the magnetic moment of the magnetosome chain.
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Affiliation(s)
- Johannes Loehr
- Experimentalphysik V, University of Bayreuth, 95440 Bayreuth, Germany.
| | - Daniel Pfeiffer
- Experimentalphysik V, University of Bayreuth, 95440 Bayreuth, Germany.
| | - Dirk Schüler
- Experimentalphysik V, University of Bayreuth, 95440 Bayreuth, Germany.
| | - Thomas M Fischer
- Experimentalphysik V, University of Bayreuth, 95440 Bayreuth, Germany.
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18
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Encapsulation as a Strategy for the Design of Biological Compartmentalization. J Mol Biol 2015; 428:916-27. [PMID: 26403362 DOI: 10.1016/j.jmb.2015.09.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/16/2015] [Accepted: 09/03/2015] [Indexed: 02/06/2023]
Abstract
Compartmentalization is one of the defining features of life. Through intracellular spatial control, cells are able to organize and regulate their metabolism. One of the most broadly used organizational principles in nature is encapsulation. Cellular processes can be encapsulated within either membrane-bound organelles or proteinaceous compartments that create distinct microenvironments optimized for a given task. Further challenges addressed through intracellular compartmentalization are toxic or volatile pathway intermediates, slow turnover rates and competing side reactions. This review highlights a selection of naturally occurring membrane- and protein-based encapsulation systems in microbes and their recent applications and emerging opportunities in synthetic biology. We focus on examples that use engineered cellular organization to control metabolic pathway flux for the production of useful compounds and materials.
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19
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Lefèvre CT, Bennet M, Landau L, Vach P, Pignol D, Bazylinski DA, Frankel RB, Klumpp S, Faivre D. Diversity of magneto-aerotactic behaviors and oxygen sensing mechanisms in cultured magnetotactic bacteria. Biophys J 2015; 107:527-538. [PMID: 25028894 DOI: 10.1016/j.bpj.2014.05.043] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/21/2014] [Accepted: 05/29/2014] [Indexed: 11/15/2022] Open
Abstract
Microorganisms living in gradient environments affect large-scale processes, including the cycling of elements such as carbon, nitrogen or sulfur, the rates and fate of primary production, and the generation of climatically active gases. Aerotaxis is a common adaptation in organisms living in the oxygen gradients of stratified environments. Magnetotactic bacteria are such gradient-inhabiting organisms that have a specific type of aerotaxis that allows them to compete at the oxic-anoxic interface. They biomineralize magnetosomes, intracellular membrane-coated magnetic nanoparticles, that comprise a permanent magnetic dipole that causes the cells to align along magnetic field lines. The magnetic alignment enables them to efficiently migrate toward an optimal oxygen concentration in microaerobic niches. This phenomenon is known as magneto-aerotaxis. Magneto-aerotaxis has only been characterized in a limited number of available cultured strains. In this work, we characterize the magneto-aerotactic behavior of 12 magnetotactic bacteria with various morphologies, phylogenies, physiologies, and flagellar apparatus. We report six different magneto-aerotactic behaviors that can be described as a combination of three distinct mechanisms, including the reported (di-)polar, axial, and a previously undescribed mechanism we named unipolar. We implement a model suggesting that the three magneto-aerotactic mechanisms are related to distinct oxygen sensing mechanisms that regulate the direction of cells' motility in an oxygen gradient.
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Affiliation(s)
- Christopher T Lefèvre
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany; CEA/CNRS/Aix-Marseille Université, UMR7265 Biologie Végétale et Microbiologie Environnementales, Laboratoire de Bioénergétique Cellulaire, Saint Paul lez Durance, France
| | - Mathieu Bennet
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Livnat Landau
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany; Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Peter Vach
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - David Pignol
- CEA/CNRS/Aix-Marseille Université, UMR7265 Biologie Végétale et Microbiologie Environnementales, Laboratoire de Bioénergétique Cellulaire, Saint Paul lez Durance, France
| | - Dennis A Bazylinski
- University of Nevada at Las Vegas, School of Life Sciences, Las Vegas, Nevada
| | - Richard B Frankel
- Department of Physics, California Polytechnic State University, San Luis Obispo, California
| | - Stefan Klumpp
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Damien Faivre
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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20
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Bain J, Staniland SS. Bioinspired nanoreactors for the biomineralisation of metallic-based nanoparticles for nanomedicine. Phys Chem Chem Phys 2015; 17:15508-21. [PMID: 25865599 DOI: 10.1039/c5cp00375j] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review explores the synthesis of inorganic metallic-based nanoparticles (MBNPs) (metals, alloys, metal oxides) using biological and biologically inspired nanoreactors for precipitation/crystallisation. Such nanoparticles exhibit a range of nanoscale properties such as surface plasmon resonance (nobel metals e.g. Au), fluorescence (semiconductor quantum dots e.g. CdSe) and nanomagnetism (magnetic alloys e.g. CoPt and iron oxides e.g. magnetite), which are currently the subject of intensive research for their applicability in diagnostic and therapeutic nanomedicine. For such applications, MBNPs are required to be biocompatible, of a precise size and shape for a consistent signal or output and be easily modified with biomolecules for applications. Ideally the MBNPs would be obtained via an environmentally-friendly synthetic route. A biological or biologically inspired nanoreactor synthesis of MBNPs is shown to address these issues. Biological nanoreactors for crystallizing MBNPs within cells (magnetosomes), protein cages (ferritin) and virus capsids (cowpea chlorotic mottle, cowpea mosaic and tobacco mosaic viruses), are discussed along with how these have been modified for applications and for the next generation of new materials. Biomimetic liposome, polymersome and even designed self-assembled proteinosome nanoreactors are also reviewed for MBNP crystallisation and further modification for applications. With the advent of synthetic biology, the research and understanding in this field is growing, with the goal of realising nanoreactor synthesis of MBNPs for biomedical applications within our grasp in the near future.
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Affiliation(s)
- Jennifer Bain
- Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK.
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21
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Zhu X, Ge X, Li N, Wu LF, Luo C, Ouyang Q, Tu Y, Chen G. Angle sensing in magnetotaxis of Magnetospirillum magneticum AMB-1. Integr Biol (Camb) 2014; 6:706-13. [PMID: 24877161 PMCID: PMC4134682 DOI: 10.1039/c3ib40259b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanism of how magnetotactic bacteria navigate along the magnetic field has been a puzzle. Two main models disagree on whether the magnetotactic behavior results from passive alignment with the magnetic field or active sensing of the magnetic force. Here, we quantitatively studied the swimming patterns of Magnetospirillum magneticum AMB-1 cells to understand the origin of their magnetotactic behaviors. Single-cell tracking and swimming pattern analysis showed that the cells follow a mixed run-reverse-tumble pattern. The average run time decreased with the angle between the cell's moving velocity and the external magnetic field. For mutant cells without the methyl-accepting chemotaxis protein (MCP) Amb0994, such dependence disappeared and bacteria failed to align with magnetic field lines. This dysfunction was recovered by complementary Amb0994 on a plasmid. At high magnetic field (>5 mT), all strains with intact magnetosome chains (including the Δamb0994-0995 strains) showed alignment with the external magnetic field. These results suggested that the mechanism for magnetotaxis is magnetic field dependent. Due to the magnetic dipole moment of the cell, the external magnetic field exerts a torque on the cell. In high magnetic fields, this torque is large enough to overcome the random re-orientation of the cell, and the cells align passively with the external magnetic field, much like a compass. In smaller (and biologically more relevant) external fields, the external force alone is not strong enough to align the cell mechanically. However, magnetotactic behaviors persist due to an active sensing mechanism in which the cell senses the torque by Amb0994 and actively regulates the flagella bias accordingly to align its orientation with the external magnetic field. Our results reconciled the two putative models for magnetotaxis and revealed a key molecular component in the underlying magneto-sensing pathway.
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Affiliation(s)
- Xuejun Zhu
- Center for the Quantitative Biology and Peking-Tsinghua Center for Life Sciences at Peking University, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
- Center for Microfluidic and Nanotechnology, The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
| | - Xin Ge
- State Key Laboratory of Microbial and Technology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
| | - Ning Li
- Center for the Quantitative Biology and Peking-Tsinghua Center for Life Sciences at Peking University, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
- Center for Microfluidic and Nanotechnology, The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
| | - Long-Fei Wu
- Laboratoire de Chimie Bacterienne, UMR7283, Aix-Marseille University, Mediterranean Microbiology Institute, CNRS, Marseille, 130009, France
| | - Chunxiong Luo
- Center for the Quantitative Biology and Peking-Tsinghua Center for Life Sciences at Peking University, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
- Center for Microfluidic and Nanotechnology, The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
| | - Qi Ouyang
- Center for the Quantitative Biology and Peking-Tsinghua Center for Life Sciences at Peking University, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
- Center for Microfluidic and Nanotechnology, The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
| | - Yuhai Tu
- Center for the Quantitative Biology and Peking-Tsinghua Center for Life Sciences at Peking University, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
- T. J. Watson Research Center, IBM, P.O. Box 218, Yorktown Heights, NY 10598
| | - Guanjun Chen
- State Key Laboratory of Microbial and Technology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
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22
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Abstract
Magnetotactic bacteria (MTB) use passive alignment with the Earth magnetic field as a mean to increase their navigation efficiency in horizontally stratified environments through what is known as magneto-aerotaxis (M-A). Current M-A models have been derived from MTB observations in aqueous environments, where a >80% alignment with inclined magnetic field lines produces a one-dimensional search for optimal living conditions. However, the mean magnetic alignment of MTB in their most widespread living environment, i.e. sediment, has been recently found to be <1%, greatly reducing or even eliminating the magnetotactic advantage deduced for the case of MTB in water. In order to understand the role of magnetotaxis for MTB populations living in sediment, we performed first M-A observations with lake sediment microcosms. Microcosm experiments were based on different combinations of (1) MTB position with respect to their preferred living depth (i.e. above, at, and below), and (2) magnetic field configurations (i.e. correctly and incorrectly polarized vertical fields, horizontal fields, and zero fields). Results suggest that polar magnetotaxis is more complex than implied by previous experiments, and revealed unexpected differences between two types of MTB living in the same sediment. Our main findings are: (1) all investigated MTB benefit of a clear magnetotactic advantage when they need to migrate over macroscopic distances for reaching their optimal living depth, (2) magnetotaxis is not used by all MTB under stationary, undisturbed conditions, (3) some MTB can rely only on chemotaxis for macroscopic vertical displacements in sediment while other cannot, and (4) some MTB use a fixed polar M-A mechanisms, while other can switch their M-A polarity, performing what can be considered as a mixed polar-axial M-A. These observations demonstrate that sedimentary M-A is controlled by complex mechanical, chemical, and temporal factors that are poorly reproduced in aqueous environments.
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23
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Bennet M, McCarthy A, Fix D, Edwards MR, Repp F, Vach P, Dunlop JWC, Sitti M, Buller GS, Klumpp S, Faivre D. Influence of magnetic fields on magneto-aerotaxis. PLoS One 2014; 9:e101150. [PMID: 24983865 PMCID: PMC4077765 DOI: 10.1371/journal.pone.0101150] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 06/03/2014] [Indexed: 11/18/2022] Open
Abstract
The response of cells to changes in their physico-chemical micro-environment is essential to their survival. For example, bacterial magnetotaxis uses the Earth's magnetic field together with chemical sensing to help microorganisms move towards favoured habitats. The studies of such complex responses are lacking a method that permits the simultaneous mapping of the chemical environment and the response of the organisms, and the ability to generate a controlled physiological magnetic field. We have thus developed a multi-modal microscopy platform that fulfils these requirements. Using simultaneous fluorescence and high-speed imaging in conjunction with diffusion and aerotactic models, we characterized the magneto-aerotaxis of Magnetospirillum gryphiswaldense. We assessed the influence of the magnetic field (orientation; strength) on the formation and the dynamic of a micro-aerotactic band (size, dynamic, position). As previously described by models of magnetotaxis, the application of a magnetic field pointing towards the anoxic zone of an oxygen gradient results in an enhanced aerotaxis even down to Earth's magnetic field strength. We found that neither a ten-fold increase of the field strength nor a tilt of 45° resulted in a significant change of the aerotactic efficiency. However, when the field strength is zeroed or when the field angle is tilted to 90°, the magneto-aerotaxis efficiency is drastically reduced. The classical model of magneto-aerotaxis assumes a response proportional to the cosine of the angle difference between the directions of the oxygen gradient and that of the magnetic field. Our experimental evidence however shows that this behaviour is more complex than assumed in this model, thus opening up new avenues for research.
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Affiliation(s)
- Mathieu Bennet
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Aongus McCarthy
- Institute of Photonics and Quantum Sciences, and Scottish Universities Physics Alliance (SUPA), School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
| | - Dmitri Fix
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Matthew R. Edwards
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Felix Repp
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Peter Vach
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - John W. C. Dunlop
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Metin Sitti
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Gerald S. Buller
- Institute of Photonics and Quantum Sciences, and Scottish Universities Physics Alliance (SUPA), School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
| | - Stefan Klumpp
- Department of Theory and Bio-systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Damien Faivre
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
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24
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Moisescu C, Ardelean II, Benning LG. The effect and role of environmental conditions on magnetosome synthesis. Front Microbiol 2014; 5:49. [PMID: 24575087 PMCID: PMC3920197 DOI: 10.3389/fmicb.2014.00049] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 01/23/2014] [Indexed: 12/14/2022] Open
Abstract
Magnetotactic bacteria (MTB) are considered the model species for the controlled biomineralization of magnetic Fe oxide (magnetite, Fe3O4) or Fe sulfide (greigite, Fe3S4) nanocrystals in living organisms. In MTB, magnetic minerals form as membrane-bound, single-magnetic domain crystals known as magnetosomes and the synthesis of magnetosomes by MTB is a highly controlled process at the genetic level. Magnetosome crystals reveal highest purity and highest quality magnetic properties and are therefore increasingly sought after as novel nanoparticulate biomaterials for industrial and medical applications. In addition, "magnetofossils," have been used as both past terrestrial and potential Martian life biosignature. However, until recently, the general belief was that the morphology of mature magnetite crystals formed by MTB was largely unaffected by environmental conditions. Here we review a series of studies that showed how changes in environmental factors such as temperature, pH, external Fe concentration, external magnetic fields, static or dynamic fluid conditions, and nutrient availability or concentrations can all affect the biomineralization of magnetite magnetosomes in MTB. The resulting variations in magnetic nanocrystals characteristics can have consequence both for their commercial value but also for their use as indicators for ancient life. In this paper we will review the recent findings regarding the influence of variable chemical and physical environmental control factors on the synthesis of magnetosome by MTB, and address the role of MTB in the global biogeochemical cycling of iron.
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Affiliation(s)
- Cristina Moisescu
- Department of Microbiology, Institute of Biology BucharestBucharest, Romania
| | - Ioan I. Ardelean
- Department of Microbiology, Institute of Biology BucharestBucharest, Romania
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25
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Nadkarni R, Barkley S, Fradin C. A comparison of methods to measure the magnetic moment of magnetotactic bacteria through analysis of their trajectories in external magnetic fields. PLoS One 2013; 8:e82064. [PMID: 24349185 PMCID: PMC3861366 DOI: 10.1371/journal.pone.0082064] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 10/21/2013] [Indexed: 11/18/2022] Open
Abstract
Magnetotactic bacteria possess organelles called magnetosomes that confer a magnetic moment on the cells, resulting in their partial alignment with external magnetic fields. Here we show that analysis of the trajectories of cells exposed to an external magnetic field can be used to measure the average magnetic dipole moment of a cell population in at least five different ways. We apply this analysis to movies of Magnetospirillum magneticum AMB-1 cells, and compare the values of the magnetic moment obtained in this way to that obtained by direct measurements of magnetosome dimension from electron micrographs. We find that methods relying on the viscous relaxation of the cell orientation give results comparable to that obtained by magnetosome measurements, whereas methods relying on statistical mechanics assumptions give systematically lower values of the magnetic moment. Since the observed distribution of magnetic moments in the population is not sufficient to explain this discrepancy, our results suggest that non-thermal random noise is present in the system, implying that a magnetotactic bacterial population should not be considered as similar to a paramagnetic material.
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Affiliation(s)
- Rohan Nadkarni
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Solomon Barkley
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Cécile Fradin
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
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26
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Kalirai SS, Bazylinski DA, Hitchcock AP. Anomalous magnetic orientations of magnetosome chains in a magnetotactic bacterium: Magnetovibrio blakemorei strain MV-1. PLoS One 2013; 8:e53368. [PMID: 23308202 PMCID: PMC3540082 DOI: 10.1371/journal.pone.0053368] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 11/30/2012] [Indexed: 11/19/2022] Open
Abstract
There is a good deal of published evidence that indicates that all magnetosomes within a single cell of a magnetotactic bacterium are magnetically oriented in the same direction so that they form a single magnetic dipole believed to assist navigation of the cell to optimal environments for their growth and survival. Some cells of the cultured magnetotactic bacterium Magnetovibrio blakemorei strain MV-1 are known to have relatively wide gaps between groups of magnetosomes that do not seem to interfere with the larger, overall linear arrangement of the magnetosomes along the long axis of the cell. We determined the magnetic orientation of the magnetosomes in individual cells of this bacterium using Fe 2p X-ray magnetic circular dichroism (XMCD) spectra measured with scanning transmission X-ray microscopy (STXM). We observed a significant number of cases in which there are sub-chains in a single cell, with spatial gaps between them, in which one or more sub-chains are magnetically polarized opposite to other sub-chains in the same cell. These occur with an estimated frequency of 4.0±0.2%, based on a sample size of 150 cells. We propose possible explanations for these anomalous cases which shed insight into the mechanisms of chain formation and magnetic alignment.
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Affiliation(s)
- Samanbir S. Kalirai
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Dennis A. Bazylinski
- School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, Nevada, United States of America
| | - Adam P. Hitchcock
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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27
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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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28
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Sonkaria S, Fuentes G, Verma C, Narang R, Khare V, Fischer A, Faivre D. Insight into the assembly properties and functional organisation of the magnetotactic bacterial actin-like homolog, MamK. PLoS One 2012; 7:e34189. [PMID: 22586444 PMCID: PMC3346761 DOI: 10.1371/journal.pone.0034189] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 02/23/2012] [Indexed: 12/22/2022] Open
Abstract
Magnetotactic bacteria (MTB) synthesize magnetosomes, which are intracellular vesicles comprising a magnetic particle. A series of magnetosomes arrange themselves in chains to form a magnetic dipole that enables the cell to orient itself along the Earth's magnetic field. MamK, an actin-like homolog of MreB has been identified as a central component in this organisation. Gene deletion, fluorescence microscopy and in vitro studies have yielded mechanistic differences in the filament assembly of MamK with other bacterial cytoskeletal proteins within the cell. With little or no information on the structural and behavioural characteristics of MamK outside the cell, the mamK gene from Magnetospirillium gryphiswaldense was cloned and expressed to better understand the differences in the cytoskeletal properties with its bacterial homologues MreB and acitin. Despite the low sequence identity shared between MamK and MreB (22%) and actin (18%), the behaviour of MamK monitored by light scattering broadly mirrored that of its bacterial cousin MreB primarily in terms of its pH, salt, divalent metal-ion and temperature dependency. The broad size variability of MamK filaments revealed by light scattering studies was supported by transmission electron microscopy (TEM) imaging. Filament morphology however, indicated that MamK conformed to linearly orientated filaments that appeared to be distinctly dissimilar compared to MreB suggesting functional differences between these homologues. The presence of a nucleotide binding domain common to actin-like proteins was demonstrated by its ability to function both as an ATPase and GTPase. Circular dichroism and structural homology modelling showed that MamK adopts a protein fold that is consistent with the 'classical' actin family architecture but with notable structural differences within the smaller domains, the active site region and the overall surface electrostatic potential.
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Affiliation(s)
- Sanjiv Sonkaria
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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Basore JR, Baker LA. Applications of microelectromagnetic traps. Anal Bioanal Chem 2012; 403:2077-88. [DOI: 10.1007/s00216-012-6040-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/30/2012] [Accepted: 04/10/2012] [Indexed: 11/28/2022]
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Analysis of the CtrA pathway in Magnetospirillum reveals an ancestral role in motility in alphaproteobacteria. J Bacteriol 2012; 194:2973-86. [PMID: 22467786 DOI: 10.1128/jb.00170-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Developmental events across the prokaryotic life cycle are highly regulated at the transcriptional and posttranslational levels. Key elements of a few regulatory networks are conserved among phylogenetic groups of bacteria, although the features controlled by these conserved systems are as diverse as the organisms encoding them. In this work, we probed the role of the CtrA regulatory network, conserved throughout the Alphaproteobacteria, in the magnetotactic bacterium Magnetospirillum magneticum strain AMB-1, which possesses unique intracellular organization and compartmentalization. While we have shown that CtrA in AMB-1 is not essential for viability, it is required for motility, and its putative phosphorylation state dictates the ability of CtrA to activate the flagellar biosynthesis gene cascade. Gene expression analysis of strains expressing active and inactive CtrA alleles points to the composition of the extended CtrA regulon, including both direct and indirect targets. These results, combined with a bioinformatic study of the AMB-1 genome, enabled the prediction of an AMB-1-specific CtrA binding site. Further, phylogenetic studies comparing CtrA sequences from alphaproteobacteria in which the role of CtrA has been experimentally examined reveal an ancestral role of CtrA in the regulation of motility and suggest that its essential functions in other alphaproteobacteria were acquired subsequently.
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Komeili A. Molecular mechanisms of compartmentalization and biomineralization in magnetotactic bacteria. FEMS Microbiol Rev 2012; 36:232-55. [PMID: 22092030 DOI: 10.1111/j.1574-6976.2011.00315.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Magnetotactic bacteria (MB) are remarkable organisms with the ability to exploit the earth's magnetic field for navigational purposes. To do this, they build specialized compartments called magnetosomes that consist of a lipid membrane and a crystalline magnetic mineral. These organisms have the potential to serve as models for the study of compartmentalization as well as biomineralization in bacteria. Additionally, they offer the opportunity to design applications that take advantage of the particular properties of magnetosomes. In recent years, a sustained effort to identify the molecular basis of this process has resulted in a clearer understanding of the magnetosome formation and biomineralization. Here, I present an overview of MB and explore the possible molecular mechanisms of membrane remodeling, protein sorting, cytoskeletal organization, iron transport, and biomineralization that lead to the formation of a functional magnetosome organelle.
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Affiliation(s)
- Arash Komeili
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
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Uebe R, Henn V, Schüler D. The MagA protein of Magnetospirilla is not involved in bacterial magnetite biomineralization. J Bacteriol 2012; 194:1018-23. [PMID: 22194451 PMCID: PMC3294778 DOI: 10.1128/jb.06356-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/13/2011] [Indexed: 11/20/2022] Open
Abstract
Magnetotactic bacteria have the ability to orient along geomagnetic field lines based on the formation of magnetosomes, which are intracellular nanometer-sized, membrane-enclosed magnetic iron minerals. The formation of these unique bacterial organelles involves several processes, such as cytoplasmic membrane invagination and magnetosome vesicle formation, the accumulation of iron in the vesicles, and the crystallization of magnetite. Previous studies suggested that the magA gene encodes a magnetosome-directed ferrous iron transporter with a supposedly essential function for magnetosome formation in Magnetospirillum magneticum AMB-1 that may cause magnetite biomineralization if expressed in mammalian cells. However, more recent studies failed to detect the MagA protein among polypeptides associated with the magnetosome membrane and did not identify magA within the magnetosome island, a conserved genomic region that is essential for magnetosome formation in magnetotactic bacteria. This raised increasing doubts about the presumptive role of magA in bacterial magnetosome formation, which prompted us to reassess MagA function by targeted deletion in Magnetospirillum magneticum AMB-1 and Magnetospirillum gryphiswaldense MSR-1. Contrary to previous reports, magA mutants of both strains still were able to form wild-type-like magnetosomes and had no obvious growth defects. This unambiguously shows that magA is not involved in magnetosome formation in magnetotactic bacteria.
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Affiliation(s)
- René Uebe
- Ludwig Maximillian University Munich, Department of Biology I, Großhaderner Str. 2, D-82152 Martinsried, Germany
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Ge X, Wang K, Bo T, Kou Y, Liu W, Chen G. Magnetospirillum magneticum AMB-1 peroxiredoxins contribute to the aerotolerance and genetic stability of the genomic magnetosome island. FEMS Microbiol Lett 2011; 320:118-27. [DOI: 10.1111/j.1574-6968.2011.02298.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Quinlan A, Murat D, Vali H, Komeili A. The HtrA/DegP family protease MamE is a bifunctional protein with roles in magnetosome protein localization and magnetite biomineralization. Mol Microbiol 2011; 80:1075-87. [PMID: 21414040 DOI: 10.1111/j.1365-2958.2011.07631.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Magnetotactic bacteria contain nanometre-sized, membrane-bound organelles, called magnetosomes, which are tasked with the biomineralization of small crystals of the iron oxide magnetite allowing the organism to use geomagnetic field lines for navigation. A key player in this process is the HtrA/DegP family protease MamE. In its absence, Magnetospirillum magneticum str AMB-1 is able to form magnetosome membranes but not magnetite crystals, a defect previously linked to the mislocalization of magnetosome proteins. In this work we use a directed genetic approach to find that MamE, and another predicted magnetosome-associated protease, MamO, likely function as proteases in vivo. However, as opposed to the complete loss of mamE where no biomineralization is observed, the protease-deficient variant of this protein still supports the initiation and formation of small, 20 nm-sized crystals of magnetite, too small to hold a permanent magnetic dipole moment. This analysis also reveals that MamE is a bifunctional protein with a protease-independent role in magnetosome protein localization and a protease-dependent role in maturation of small magnetite crystals. Together, these results imply the existence of a previously unrecognized 'checkpoint' in biomineralization where MamE moderates the completion of magnetite formation and thus committal to magneto-aerotaxis as the organism's dominant mode of navigating the environment.
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Affiliation(s)
- Anna Quinlan
- Department of Molecular and Cell Biology, University of California Berkeley, 111 Koshland Hall, Berkeley, CA 94720, USA
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Comprehensive genetic dissection of the magnetosome gene island reveals the step-wise assembly of a prokaryotic organelle. Proc Natl Acad Sci U S A 2010; 107:5593-8. [PMID: 20212111 DOI: 10.1073/pnas.0914439107] [Citation(s) in RCA: 205] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although membrane-bounded compartments are commonly considered a unique eukaryotic characteristic, many species of bacteria have organelles. Compartmentalization is well studied in eukaryotes; however, the molecular factors and processes leading to organelle formation in bacteria are poorly understood. We use the magnetosome compartments of magnetotactic bacteria as a model system to investigate organelle biogenesis in a prokaryotic system. The magnetosome is an invagination of the cell membrane that contains a specific set of proteins able to direct the synthesis of a nanometer-sized magnetite crystal. A well-conserved region called the magnetosome island (MAI) is known to be essential for magnetosome formation and contains most of the genes previously implicated in magnetosome formation. Here, we present a comprehensive functional analysis of the MAI genes in a magnetotactic bacterium, Magnetospirillum magneticum AMB-1. By characterizing MAI deletion mutants, we show that parts of its conserved core are not essential for magnetosome biogenesis and that nonconserved genes are important for crystal formation. Most importantly, we show that the mamAB gene cluster encodes for factors important for magnetosome membrane biogenesis, for targeting of proteins to this compartment and for several steps during magnetite production. Altogether, this genetic analysis defines the function of more than a dozen factors participating in magnetosome formation and shows that magnetosomes are assembled in a step-wise manner in which membrane biogenesis, magnetosome protein localization, and biomineralization are placed under discrete genetic control.
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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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Benoit MR, Mayer D, Barak Y, Chen IY, Hu W, Cheng Z, Wang SX, Spielman DM, Gambhir SS, Matin A. Visualizing implanted tumors in mice with magnetic resonance imaging using magnetotactic bacteria. Clin Cancer Res 2009; 15:5170-7. [PMID: 19671860 DOI: 10.1158/1078-0432.ccr-08-3206] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PURPOSE To determine if magnetotactic bacteria can target tumors in mice and provide positive contrast for visualization using magnetic resonance imaging. EXPERIMENTAL DESIGN The ability of the magnetotactic bacterium, Magnetospirillum magneticum AMB-1 (referred to from here as AMB-1), to confer positive magnetic resonance imaging contrast was determined in vitro and in vivo. For the latter studies, AMB-1 were injected either i.t. or i.v. Bacterial growth conditions were manipulated to produce small (approximately 25-nm diameter) magnetite particles, which were observed using transmission electron microscopy. Tumor targeting was confirmed using 64Cu-labeled bacteria and positron emission tomography and by determination of viable cell counts recovered from different organs and the tumor. RESULTS We show that AMB-1 bacteria with small magnetite particles generate T1-weighted positive contrast, enhancing in vivo visualization by magnetic resonance imaging. Following i.v. injection of 64Cu-labeled AMB-1, positron emission tomography imaging revealed increasing colonization of tumors and decreasing infection of organs after 4 hours. Viable cell counts showed that, by day 6, the bacteria had colonized tumors but were cleared completely from other organs. Magnetic resonance imaging showed a 1.22-fold (P = 0.003) increased positive contrast in tumors on day 2 and a 1.39-fold increase (P = 0.0007) on day 6. CONCLUSION Magnetotactic bacteria can produce positive magnetic resonance imaging contrast and colonize mouse tumor xenografts, providing a potential tool for improved magnetic resonance imaging visualization in preclinical and translational studies to track cancer.
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Affiliation(s)
- Michael R Benoit
- Department of Microbiology and Immunology, Stanford University, Stanford, California 94305-5124, USA
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Xie J, Chen K, Chen X. Production, Modification and Bio-Applications of Magnetic Nanoparticles Gestated by Magnetotactic Bacteria. NANO RESEARCH 2009; 2:261-278. [PMID: 20631916 PMCID: PMC2902887 DOI: 10.1007/s12274-009-9025-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Revised: 01/20/2009] [Accepted: 01/21/2009] [Indexed: 05/25/2023]
Abstract
Magnetotactic bacteria (MTB) were first discovered by Richard P. Blakemore in 1975, and this led to the discovery of a wide collection of microorganisms with similar features i.e., the ability to internalize Fe and convert it into magnetic nanoparticles, in the form of either magnetite (Fe(3)O(4)) or greigite (Fe(3)S(4)). Studies showed that these particles are highly crystalline, monodisperse, bioengineerable and have high magnetism that is comparable to those made by advanced synthetic methods, making them candidate materials for a broad range of bio-applications. In this review article, the history of the discovery of MTB and subsequent efforts to elucidate the mechanisms behind the magnetosome formation are briefly covered. The focus is on how to utilize the knowledge gained from fundamental studies to fabricate functional MTB nanoparticles (MTB-NPs) that are capable of tackling real biomedical problems.
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Affiliation(s)
- Jin Xie
- Department of Radiology, Bio-X Program, Stanford University School of Medicine, Stanford, CA 94305-5484, USA
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Ardelean I, Moisescu C, Ignat M, Constantin M, Virgolici M. Magnetospirillum Gryphiswaldense:Fundamentals and Applications. BIOTECHNOL BIOTEC EQ 2009. [DOI: 10.1080/13102818.2009.10818532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Affiliation(s)
- Damien Faivre
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
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Abstract
AbstractThe ability to respond to magnetic fields is ubiquitous among the five kingdoms of organisms. Apart from the mechanisms that are at work in bacterial magnetotaxis, none of the innumerable magnetobiological effects are as yet completely understood in terms of their underlying physical principles. Physical theories on magnetoreception, which draw on classical electrodynamics as well as on quantum electrodynamics, have greatly advanced during the past twenty years, and provide a basis for biological experimentation. This review places major emphasis on theories, and magnetobiological effects that occur in response to weak and moderate magnetic fields, and that are not related to magnetotaxis and magnetosomes. While knowledge relating to bacterial magnetotaxis has advanced considerably during the past 27 years, the biology of other magnetic effects has remained largely on a phenomenological level, a fact that is partly due to a lack of model organisms and model responses; and in great part also to the circumstance that the biological community at large takes little notice of the field, and in particular of the available physical theories. We review the known magnetobiological effects for bacteria, protists and fungi, and try to show how the variegated empirical material could be approached in the framework of the available physical models.
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Abstract
Magnetotactic bacteria are a diverse group of microorganisms with the ability to use geomagnetic fields for direction sensing. This unique feat is accomplished with the help of magnetosomes, nanometer-sized magnetic crystals surrounded by a lipid bilayer membrane and organized into chains via a dedicated cytoskeleton within the cell. Because of the special properties of these magnetic crystals, magnetotactic bacteria have been exploited for a variety of applications in diverse disciplines from geobiology to biotechnology. In addition, magnetosomes have served as a powerful model system for the study of biomineralization and cell biology in bacteria. This review focuses on recent advances in understanding the molecular mechanisms of magnetosome formation and magnetite biomineralization.
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Affiliation(s)
- Arash Komeili
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
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Erglis K, Wen Q, Ose V, Zeltins A, Sharipo A, Janmey PA, Cēbers A. Dynamics of magnetotactic bacteria in a rotating magnetic field. Biophys J 2007; 93:1402-12. [PMID: 17526564 PMCID: PMC1929029 DOI: 10.1529/biophysj.107.107474] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 04/17/2007] [Indexed: 11/18/2022] Open
Abstract
The dynamics of the motile magnetotactic bacterium Magnetospirillum gryphiswaldense in a rotating magnetic field is investigated experimentally and analyzed by a theoretical model. These elongated bacteria are propelled by single flagella at each bacterial end and contain a magnetic filament formed by a linear assembly of approximately 40 ferromagnetic nanoparticles. The movements of the bacteria in suspension are analyzed by consideration of the orientation of their magnetic dipoles in the field, the hydrodynamic resistance of the bacteria, and the propulsive force of the flagella. Several novel features found in experiments include a velocity reversal during motion in the rotating field and an interesting diffusive wandering of the trajectory curvature centers. A new method to measure the magnetic moment of an individual bacterium is proposed based on the theory developed.
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