Topic
Magnetotactic bacteria
About: Magnetotactic bacteria is a research topic. Over the lifetime, 1118 publications have been published within this topic receiving 43741 citations.
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13 Apr 1993
TL;DR: In this article, the response of magnetotactic bacteria to an applied magnetic field has been analyzed using image processing techniques, including magnetic movement, and magnetic properties of the bacteria with a higher rate and with greater accuracy.
Abstract: The response of magnetotactic bacteria to an applied magnetic field has been analyzed using image processing techniques. Bacterial characteristics, including magnetic movement, have been processed at a higher rate and evaluated with greater accuracy. This method offers a unique tool in data analysis and enhancement for recorded images of biological systems. >
27 citations
TL;DR: The results demonstrated that the M. magneticum AMB-1 responded to light as well as other environmental factors, the first report of phototactic behavior in the bacteria of Magnetospirillum, and was independent of magnetotaxis.
Abstract: Magnetotactic bacteria (MTB) can rapidly relocate to optimal habitats by magneto-aerotaxis. Little is known about MTB phototaxis, a response that might also aid navigation. In this study, we analyzed the relationship between phototaxis and magnetotaxis in Magnetospirillum magneticum strain AMB-1. Magnotactic AMB-1 cells migrated toward light, and migration increased with higher light intensity. This response was independent of wavelength, as AMB-1 cells migrated equally toward light from 400 to 750 nm. When AMB-1 cells were exposed to zero magnetic fields or to 0.2 mT magnetic fields that were opposite or orthogonal to the light beam, cells still migrated toward the light, indicating that phototaxis was independent of magnetotaxis. The R
mag value and coercive force (H
c) of AMB-1 increased when the bacteria were illuminated for 20 h, consistent with an increase in magnetosome synthesis or in magnetosome-containing cells. These results demonstrated that the M. magneticum AMB-1 responded to light as well as other environmental factors. To our knowledge, this is the first report of phototactic behavior in the bacteria of Magnetospirillum.
26 citations
TL;DR: A robust and tunable microfluidic sorting system in which magnetic gradients of up to 1700 T/m can be applied to cells flowing through a sorting channel by reversible magnetization of ferrofluids, which ensures contamination-free separation of naturally occurring or bioengineered magnetic cells and is essential for downstream characterization of their properties.
Abstract: Magnetic cell sorting provides a valuable complementary mechanism to fluorescent techniques, especially if its parameters can be fine-tuned. In addition, there has recently been growing interest in studying naturally occurring magnetic cells and genetic engineering of cells to render them magnetic in order to control molecular processes via magnetic fields. For such approaches, contamination-free magnetic separation is an essential capability. We here present a robust and tunable microfluidic sorting system in which magnetic gradients of up to 1700 T/m can be applied to cells flowing through a sorting channel by reversible magnetization of ferrofluids. Visual control of the sorting process allowed us to optimize sorting efficiencies for a large range of sizes and magnetic moments of cells. Using automated quantification based on imaging of fluorescent markers, we showed that macrophages containing phagocytosed magnetic nanoparticles, with cellular magnetic dipole moments on the order of 10 fAm2, could be sorted with an efficiency of 90 ± 1%. Furthermore, we successfully sorted intrinsically magnetic magnetotactic bacteria with magnetic moments of 0.1 fAm2. In distinction to column-based magnetic sorting devices, microfluidic systems can prevent sample contact with superparamagnetic material. This ensures contamination-free separation of naturally occurring or bioengineered magnetic cells and is essential for downstream characterization of their properties.
26 citations
TL;DR: These results demonstrate for the first time that magnetosomes can be employed as scaffolds for the display of multisubunit complexes.
Abstract: Magnetosomes are unique bacterial organelles comprising membrane-enveloped magnetic crystals produced by magnetotactic bacteria. Because of several desirable chemical and physical properties, magnetosomes would be ideal scaffolds on which to display highly complicated biological complexes artificially. As a model experiment for the functional expression of a multisubunit complex on magnetosomes, we examined the display of a chimeric bacterial RNase P enzyme composed of the protein subunit (C5) of Escherichia coli RNase P and the endogenous RNA subunit by expressing a translational fusion of C5 with MamC, a known magnetosome protein, in the magnetotactic bacterium Magnetospirillum gryphiswaldense. As intended, the purified C5 fusion magnetosomes, but not wild-type magnetosomes, showed apparent RNase P activity and the association of a typical bacterial RNase P RNA. Our results demonstrate for the first time that magnetosomes can be employed as scaffolds for the display of multisubunit complexes.
26 citations
TL;DR: The magnetotactic bacterium A. magnetoticum contains ferrous ions, a low density hydrous ferric oxide (ferrihydrite), and Fe $\_3$ O $\_4$, which is precipitated by partial reduction of the ferrihydite precursor as discussed by the authors.
Abstract: The magnetotactic bacterium A. magnetotacticum contains ferrous ions, a low density hydrous ferric oxide, a high density hydrous ferric oxide (ferrihydrite) and Fe $\_3$ O $\_4$ , which is precipitated by partial reduction of the ferrihydrite precursor.
26 citations