Magnetic Microstructure of Magnetotactic Bacteria by Electron Holography

Electron Holography of Magnetic Materials

“…Although the crystals in the cell are less well organized with respect to their morphology, crystallographic orientation and position, when compared with magnetiteproducing bacteria, they provide a measured collective magnetic moment (~9 x 10 -16 Am 2 ) that is sufficient for magnetotaxis and is calculated to allow the cell to migrate along geomagnetic field lines at more than 90% of its forward speed. The magnetic moment and forward speed were determined using methods described by Dunin-Borkowski et al (1998) and Frankel (1984), respectively. These results provide new insight for understanding magnetotaxis in iron sulfide-producing magnetotactic bacteria.…”

Determination of the Crystal Structure of a New Polymorph of Theophylline

“…[8] In imaging mode the technique is routinely used for identification and characterisation of defect structures; [9] in diffraction mode, detailed investigations of both symmetry [10] and crystal structure [11] are possible. Precision control of sample position and tilt, coupled with rapid acquisition of digital images, has contributed strongly to the development of holographic methods for the measurement of local fields within structures, [12] and tomographic approaches to three dimensional characterisation of microstructure. [13] Studies of inorganic materials have tended to exploit the high spatial resolution of the technique, which is now better than 0.1 nm for high performance instruments.…”

Magnetic microstructure of iron sulfide crystals in magnetotactic bacteria from off-axis electron holography

“…and di organized chain arrangement of greigite magnetoWhereas the structural and magnetic properties of magne omes differ from most magnetite-producing pecie that tite rnagnetosomes have been studied extensively [2] this is exert stricter control over the physical properties of not tbe ca e for greigite magneto orne [3]. Here we report magnetite magnetosomes [1,7 8].…”

“…The method has been applied successfully to studies of magnetite magnetosomes, and proved to be extremely useful for assessing the competing effects of crystal shape, magnetocrystalline anisotropy and interparticle interac tions in linear chains of magnetosomes [2,14].…”

“…Whereas the magnetic properties of magnetite magnetosomes have been studied in several bacterial strains [2,[11][12][13][14], little is known about the magnetic microstructure of sulfide magne tosomes [15]. In addition, some magnetic parameters of greigite, including the effect of crystal size, shape and magnetocrystalline anisotropy on magnetic microstructure, are not satisfactorily known [16].…”