Influence of the bacterial growth phase on the magnetic properties of magnetosomes synthesized by Magnetospirillum gryphiswaldense

Marcano, Lourdes; Prieto, A.; Muñoz, David G.; Barquı́n, L. Fernández; Orúe, I.; Alonso, Javier; Muela, A.; Fdez-Gubieda, M. L.

doi:10.1016/j.bbagen.2017.01.012

Cited by 26 publications

(20 citation statements)

References 30 publications

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“…Figure 4 shows the Fe K-edge XANES spectra of the whole bacteria (control and M-bacteria) and the corresponding isolated magnetosomes (control magnetosomes and M-magnetosomes). Regardless of the metal studied, all M-bacterial spectra and the spectra of their corresponding isolated M-magnetosomes are coincident with the control, which corresponds to the spectrum measured for magnetite 18,19 . The spectra of isolated M-magnetosomes being identical to magnetite regardless of the metal studied suggests that the amount of metal incorporated into the magnetosome is low, insufficient to change appreciably the coordination environment of the Fe atoms.…”

Section: Resultssupporting

confidence: 69%

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

Muñoz

Marcano

Martín-Rodríguez

et al. 2020

Sci Rep

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Magnetotactic bacteria are aquatic microorganisms with the ability to biomineralise membraneenclosed magnetic nanoparticles, called magnetosomes. these magnetosomes are arranged into a chain that behaves as a magnetic compass, allowing the bacteria to align in and navigate along the Earth's magnetic field lines. According to the magneto-aerotactic hypothesis, the purpose of producing magnetosomes is to provide the bacteria with a more efficient movement within the stratified water column, in search of the optimal positions that satisfy their nutritional requirements. However, magnetosomes could have other physiological roles, as proposed in this work. Here we analyse the role of magnetosomes in the tolerance of Magnetospirillum gryphiswaldense MSR-1 to transition metals (co, Mn, ni, Zn, cu). By exposing bacterial populations with and without magnetosomes to increasing concentrations of metals in the growth medium, we observe that the tolerance is significantly higher when bacteria have magnetosomes. The resistance mechanisms triggered in magnetosome-bearing bacteria under metal stress have been investigated by means of x-ray absorption near edge spectroscopy (XANES). XANES experiments were performed both on magnetosomes isolated from the bacteria and on the whole bacteria, aimed to assess whether bacteria use magnetosomes as metal storages, or whether they incorporate the excess metal in other cell compartments. Our findings reveal that the tolerance mechanisms are metal-specific: Mn, Zn and cu are incorporated in both the magnetosomes and other cell compartments; co is only incorporated in the magnetosomes, and Ni is incorporated in other cell compartments. In the case of Co, Zn and Mn, the metal is integrated in the magnetosome magnetite mineral core. Magnetotactic bacteria (MTB) are aquatic microorganisms able to passively align parallel to the Earth's geomagnetic field lines while they actively swim. This behavior, known as magnetotaxis, is due to the presence of unique intracellular magnetic organelles called magnetosomes 1-4. The magnetosomes are intracellular inclusions composed by a core of magnetic iron mineral, typically magnetite (Fe 3 O 4) or greigite (Fe 3 S 4), enclosed by a thin membrane. Magnetotactic bacteria are widespread in freshwater and marine environments 5. They are easily detected in chemically and redox stratified sediments and water columns, predominantly at the oxic-anoxic transition zones (OATZ). Bacteria living in OATZ, with vertical chemical gradients, are continually searching the optimal position in the stratified water column in order to satisfy their nutritional requirements. Under these circumstances, magnetotaxis is thought to be a great advantage by increasing the efficiency of chemotaxis 1. Due to their inclination, the geomagnetic field lines act as vertical pathways in a stratified environment, therefore the bacteria aligned in the Earth's field reduce a three dimensional search to a single dimension, swimming updownwards the stratified column.

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Section: Resultssupporting

confidence: 69%

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

Muñoz

Marcano

Martín-Rodríguez

et al. 2020

Sci Rep

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“…Figure 4 shows the Fe K-edge XANES spectra of the whole bacteria (control and Mbacteria) and the corresponding isolated magnetosomes (control magnetosomes and M-magnetosomes). Regardless of the metal studied, all M-bacterial spectra and the spectra of their corresponding isolated M-magnetosomes are coincident with the control, which corresponds to the spectrum measured for magnetite 18,19 . The spectra of isolated M-magnetosomes being identical to magnetite regardless of the metal studied suggests that the amount of metal incorporated into the magnetosome is low, insufficient to change appreciably the coordination environment of the Fe atoms.…”

Section: Study Of the Metal Incorporation By Xanes Spectroscopysupporting

confidence: 69%

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

ntildeoz

Marcano

iacuteguez

et al. 2020

Preprint

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Magnetotactic bacteria are aquatic microorganisms with the ability to biomineralise membrane-enclosed magnetic nanoparticles, called magnetosomes. These magnetosomes are arranged into a chain that behaves as a magnetic compass, allowing the bacteria to align in and navigate along the Earth's magnetic field lines. According to the magneto-aerotactic hypothesis, the purpose of producing magnetosomes is to provide the bacteria with a more efficient movement within the stratified water column, in search of the optimal positions that satisfy their nutritional requirements. However, magnetosomes could have other physiological roles, as proposed in this work. Here we analyse the role of magnetosomes in the tolerance of Magnetospirillum gryphiswaldense MSR-1 to transition metals (Co, Mn, Ni, Zn, Cu). By exposing bacterial populations with and without magnetosomes to increasing concentrations of metals in the growth medium, we observe that the tolerance is significantly higher when bacteria have magnetosomes. The resistance mechanisms triggered in magnetosome-bearing bacteria under metal stress have been investigated by means of x-ray absorption near edge spectroscopy (XANES). XANES experiments were performed both on magnetosomes isolated from the bacteria and on the whole bacteria, aimed to assess whether bacteria use magnetosomes as metal storages, or whether they incorporate the excess metal in other cell compartments. Our findings reveal that the tolerance mechanisms are metal-specific: Mn, Zn and Cu are incorporated in both the magnetosomes and other cell compartments; Co is only incorporated in the magnetosomes, and Ni is incorporated in other cell compartments. In the case of Co, Zn and Mn, the metal is integrated in the magnetosome magnetite mineral core.Magnetotactic bacteria (MTB) are aquatic microorganisms able to passively align parallel to the Earth's geomagnetic field lines while they actively swim. This behavior, known as magnetotaxis, is due to the presence of unique intracellular magnetic organelles called magnetosomes 1-4 . The magnetosomes are intracellular inclusions composed by a core of magnetic iron mineral, typically magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 ), enclosed by a thin membrane.Magnetotactic bacteria are widespread in freshwater and marine environments 5 . They are easily detected in chemically and redox stratified sediments and water columns, predominantly at the oxic-anoxic transition zones (OATZ). Bacteria living in OATZ, with vertical chemical gradients, are continually searching the optimal position in the stratified water column in order to satisfy their nutritional requirements. Under these circumstances, magnetotaxis is thought to be a great advantage by increasing the efficiency of chemotaxis 1 . Due to their inclination, the geomagnetic field lines act as vertical pathways in a stratified environment, therefore the bacteria aligned in the Earth's field reduce a three dimensional search to a single dimension, swimming up-downwards the stratified column.Another possible role of...

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“…These characteristics are ideal for their use as nanobiots for cancer treatment. The magnetic response of magnetotactic bacteria has also been characterized in our previous works . The magnetization versus temperature curves present a well‐defined Verwey transition around 110 K, which is a clear cut indicator of the stoichiometric magnetite structure of magnetosomes, the low dispersion on their size, and thereby, of their enhanced magnetic response.…”

Section: Resultsmentioning

confidence: 99%

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Gandia

Gandarias

Rodrigo

et al. 2019

Small

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Magnetotactic bacteria are aquatic microorganisms that internally biomineralize chains of magnetic nanoparticles (called magnetosomes) and use them as a compass. Here it is shown that magnetotactic bacteria of the strain Magnetospirillum gryphiswaldense present high potential as magnetic hyperthermia agents for cancer treatment. Their heating efficiency or specific absorption rate is determined using both calorimetric and AC magnetometry methods at different magnetic field amplitudes and frequencies. In addition, the effect of the alignment of the bacteria in the direction of the field during the hyperthermia experiments is also investigated. The experimental results demonstrate that the biological structure of the magnetosome chain of magnetotactic bacteria is perfect to enhance the hyperthermia efficiency. Furthermore, fluorescence and electron microscopy images show that these bacteria can be internalized by human lung carcinoma cells A549, and cytotoxicity studies reveal that they do not affect the viability or growth of the cancer cells. A preliminary in vitro hyperthermia study, working on clinical conditions, reveals that cancer cell proliferation is strongly affected by the hyperthermia treatment, making these bacteria promising candidates for biomedical applications.

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Influence of the bacterial growth phase on the magnetic properties of magnetosomes synthesized by Magnetospirillum gryphiswaldense

Cited by 26 publications

References 30 publications

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

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