Molecular mechanism of magnet formation in bacteria

Matsunaga, Tadashi; Sakaguchi, Toshifumi

doi:10.1016/s1389-1723(00)80001-8

Cited by 56 publications

(11 citation statements)

References 102 publications

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“…10b where 'A' and 'B' are magnetite's tetrahedral and octahedral sub-lattices. Although this oxide is well known to be connected to different types of bacterial activity [45,46], it is mainly a product of Fe (III) reduction by dissimilatory iron-reducing bacteria [47] and has never been found in FeOB by-products. The presence of traces of maghemite in the XRD spectrum can, therefore, be explained based on the results of our earlier studies [48,49], where this was determined as being an oxidized surface layer with a maghemite-like structure characteristic for magnetite nanoparticles.…”

Section: Resultsmentioning

confidence: 99%

Biogenic nanosized iron oxides obtained from cultivation of iron bacteria from the genus Leptothrix

et al. 2016

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A detailed investigation of nanostructured iron oxides/(oxy)hydroxides gathered after cultivation of bacteria from the genus Leptothrix as iron (II) oxidizers is presented. A specific type of medium is selected for the cultivation of the bacteria. Results for sediment powder and bio-film on glass substrate samples from the same media are discussed. XRD, Raman spectroscopy, SEM, and TEM images and PPMS measurements are used to prove the exact composition of the biogenic products and to interpret the oxidation process. Analysis of the data collected shows that around 80 % of the iron (II) from the growth medium has been transformed into iron (III) in the form of different (oxy)hydroxides, with the rest found to be in a mixed 2,5 valence in magnetite. Our investigation shows that the bio-film sample has a phase content different from that of the powdered biomass and that lepidocrocite (γ-FeOOH) is the predominant and the initial biogenic phase in both samples. Magnetite nanoparticles are a secondary product in the bio-film, part of which possesses a defective quasi-maghemite surface layer. In the powdered biomass, the oxidation steps are not fully completed. The initial products are non-stoichiometric and due to the mixed ferric and ferrous ions present, they develop into: (i) lepidocrocite (γ-FeOOH) as a basic sediment, (ii) magnetite (Fe 3 O 4 ) and (iii) goethite (α-FeOOH) in small quantities. The average size of all iron-bearing particles is found to be below 30 nm. The magnetic measurements performed show a superparamagnetic behavior of the material at room temperature.

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Section: Resultsmentioning

confidence: 99%

Biogenic nanosized iron oxides obtained from cultivation of iron bacteria from the genus Leptothrix

et al. 2016

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“…The size of magnetosome crystals range from about 35 to 120 nm in diameter, and appears to be under strict biological control as all magnetosome crystals, regardless of whether they consist of magnetite or greigite, are single-domain magnets [10,21,30,56]. Each species or strain exhibits a particular arrangement of magnetosomes within the [4,10,45,61].…”

Section: Introductionmentioning

confidence: 99%

“…In Magnetospirillum, it originates as an invagination of the cytoplasmic membrane and is a stable lipid bilayer 3-4 nm thick comprised of phospholipids, fatty acids, and proteins [1,29]. As previously stated, magnetosomes contain single-domain Fe 3 O 4 (or Fe 3 S 4 ) crystals and are arranged in one or more chains that cause the cells to align along the Earth's geomagnetic field [21,30,45,56]. The magnetic interactions between the individual magnetosome crystals in the chain and a complex cytoskeleton including filaments dedicated to the construction of the magnetosome chain [34,59] cause their magnetic dipole moments to orient head-to-tail along the length of the chain.…”

Section: Introductionmentioning

confidence: 99%

Collection and Enrichment of Magnetotactic Bacteria from the Environment

Oestreicher

Lower

Bazylinski

et al. 2015

Bacteria-Metal Interactions

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We describe a relatively inexpensive and effective method for collecting magnetotactic bacteria (MTB) from the field. This protocol relies on the use of simple magnets. A clear plastic container can be used to collect sediment and water from a natural source, such as a freshwater pond. In the Northern hemisphere, the south end of a bar magnet is placed against the outside of the container just above the sediment at the sediment-water interface. After some time, the bacteria can be removed from the inside of the container near the magnet with a pipette and then enriched further by using a capillary racetrack and a magnet. In the racetrack, a sterile cotton plug is used to separate magnetic versus non-magnetic cells as the MTB swim through the cotton towards a magnet placed at the opposite end of the racetrack. Once enriched, the presence of MTB can be confirmed by using the hanging drop method and a light microscope to observe MTB swimming in response to the north or south end of a bar magnet. Higher resolution can be obtained by depositing a drop of enriched MTB onto a copper grid and observing the microorganisms with transmission electron microscopy (TEM). Using this method, isolated MTB may be studied microscopically to determine characteristics such as swimming behavior, type and number of flagella, cell morphology, shape of the magnetic crystals, number of magnetosomes, number of magnetosome chains in each cell, composition of the crystals, and presence of intracellular vacuoles.

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“…The properties of these various types of intentionally produced nanomaterials and nanoparticles enable potential application in commercial, medical, environmental sectors and so forth. Nanoparticles are said to be central to many natural processes [3][4][5]. Nanoparticles are present in the environment from both natural and anthropogenic sources.…”

Section: Introductionmentioning

confidence: 99%

Nanotoxicity: Dimensional and Morphological Concerns

Wani

Hashim

Nabi

et al. 2011

Advances in Physical Chemistry

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Nanotechnology deals with the construction of new materials, devices, and different technological systems with a wide range of potential applications at the atomic and molecular level. Nanomaterials have attracted great attention for numerous applications in chemical, biological, and industrial world because of their fascinating physicochemical properties. Nanomaterials and nanodevices are being produced intentionally, unintentionally, and manufactured or engineered by different methods and released into the environment without any safety test. Nantoxicity has become the subject of concern in nanoscience and nanotechnology because of the increasing toxic effects of nanomaterials on the living organisms. Nanomaterials can move freely as compared to the largesized particles; therefore, they can be more toxic than bulky materials. This review article delineates the toxic effects of different types of nanomaterials on the living organisms through different sources, like water, air, contact with skin, and the methods of determinations of these toxic effects.

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Molecular mechanism of magnet formation in bacteria

Cited by 56 publications

References 102 publications

Biogenic nanosized iron oxides obtained from cultivation of iron bacteria from the genus Leptothrix

Biogenic nanosized iron oxides obtained from cultivation of iron bacteria from the genus Leptothrix

Collection and Enrichment of Magnetotactic Bacteria from the Environment

Nanotoxicity: Dimensional and Morphological Concerns

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