Showing papers on "Magnetotactic bacteria published in 1987"
TL;DR: The GS-15 organism as mentioned in this paper is not magnetotactic, but reduces amorphic ferric oxide to extracellular magnetite during the reduction of ferric iron as the terminal electron acceptor for organic matter oxidation.
Abstract: The potential contribution of microbial metabolism to the magnetization of sediments has only recently been recognized. In the presence of oxygen, magnetotactic bacteria can form intracellular chains of magnetite while using oxygen or nitrate as the terminal electron acceptor for metabolism1. The production of ultrafine-grained magnetite by magnetotactic bacteria in surficial aerobic sediments may contribute significantly to the natural remanent magnetism of sediments2–4. However, recent studies on iron reduction in anaerobic sediments suggested that bacteria can also generate magnetite in the absence of oxygen5. We report here on a sediment organism, designated GS-15, which produces copious quantities of ultrafine-grained magnetite under anaerobic conditions. GS-15 is not magnetotactic, but reduces amorphic ferric oxide to extracellular magnetite during the reduction of ferric iron as the terminal electron acceptor for organic matter oxidation. This novel metabolism may be the mechanism for the formation of ultrafine-grained magnetite in anaerobic sediments, and couldaccount for the accumulation of magnetite in ancient iron formations and hydrocarbon deposits.
921 citations
TL;DR: The novel use of magnetic particles isolated from magnetotactic bacteria collected from enriched sludge by use of a magnetic harvesting apparatus and glucose oxidase and uricase coupled with biogenic magnetic particles retained their activities when they were reused 5 times.
Abstract: We report the novel use of magnetic particles isolated from magnetotactic bacteria. Magnetotactic bacteria were collected from enriched sludge by use of a magnetic harvesting apparatus. Magnetic particles separated from magnetotactic bacteria were shown to be pure magnetite. Glucose oxidase and uricase were immobilized on magnetic particles. The activity of glucose oxidase immobilized on biogenic magnetites was 40 times that immobilized on artificial magnetites or Zn-ferrite particles. Both glucose oxidase and uricase coupled with biogenic magnetic particles retained their activities when they were reused 5 times.
170 citations
TL;DR: In this article, the formation of fine-grained authigenic magnetites near the commonly observed brown-tan-green colour boundary, which marks the transition from Fe-oxidizing to Fe-reducing conditions, was investigated.
Abstract: The resolution and reliability of magnetostratigraphy and reconstructed time series of geomagnetic field behaviour depend critically on where remanence is acquired and fixed in the sediment column and whether the magnetization is altered chemically after deposition. If authigenic magnetic minerals are formed at depth or if the magnetic carriers are changed after deposition, then the nature and timing of magnetic events can be affected by depth offsets in remanence acquisition and mixing of detrital and authigenic signals. Using palaeo- and rock-magnetic and sediment geochemical analyses, we have studied how early diagenesis affects the magnetic properties of suboxic hemipelagic sediments. Here, we report evidence of the formation of fine-grained authigenic magnetites near the commonly observed brown–tan-green colour boundary, which marks the transition from Fe-oxidizing to Fe-reducing conditions. We propose that biogenic magnetite, produced by magnetotactic bacteria, forms as part of the microbially mediated sequence of reactions involved in the oxidation of organic matter. The magnetite is created as a metabolic by-product of the microorganisms' use of iron redox transitions as a source of energy. Active magnetite formation appears to be restricted to a zone between the levels of nitrate and iron reduction.
170 citations
TL;DR: In this article, the authors analyzed fossil magnetosomes from living magnetotactic bacteria and found that they were morphologically similar to those from living bacteria, but seemed to be corroded in some cases.
164 citations
TL;DR: A capillary tube was developed in which an inoculum of magnetotactic bacteria that contained only a few contaminants could be separated from crude sediment in a few minutes.
Abstract: A capillary tube was developed in which an inoculum of magnetotactic bacteria that contained only a few contaminants could be separated from crude sediment in a few minutes. Sterile fluid was placed on one side of a wetted cotton plug and sediment was placed on the other side. Magnetotactic bacteria migrated quickly through the cotton toward the south pole of a stirring-bar magnet placed at the closed end of the capillary. Protozoa and chemotactic bacteria were significantly delayed in passage through the cotton.
127 citations
TL;DR: In this paper, the presence of magnetotactic bacteria and ultrafine-grained single domain magnetite in carbonate oozes and calcareous laminated sediments from Laguna Figueroa, Baja California, Mexico has been investigated.
76 citations
TL;DR: Ovoid magnetotactic bacteria extracted from the Exeter River, New Hampshire, U.S.A., contain chains of 20-35 anisotropic magnetic inclusions running longitudinally in each of three lateral cell positions adjacent to the inner surface of the cytoplasmic membrane as mentioned in this paper.
Abstract: Ovoid magnetotactic bacteria extracted from the Exeter River, New Hampshire, U.S.A., contain chains of 20-35 anisotropic magnetic inclusions running longitudinally in each of three lateral cell positions adjacent to the inner surface of the cytoplasmic membrane. The inclusions are bullet-shaped and have characteristic flattened end faces. Some particles show kinking and curvature in their morphology. In cross section the particles have a hexagonal shape. The length of the inclusions varies over a wide range (45-135 nm) with a mean value of 97.8 nm. In contrast, the width of the particles is restricted to a range of 30-45 nm with a mean value of 36.9 nm. Many particles are surrounded by an organic electrondense envelope. The crystallographic structure of the inclusions has been determined by electron diffraction and corresponds to the mineral magnetite (Fe$_{3}$O$_{4}$). The dimensions of the crystals fall within the magnetic single-domain range for magnetite and the magnetic moment of one cell is approximately 4 $\times $ 10$^{-12}$ emu (4 fJT$^{-1}$).
75 citations
TL;DR: Magnetotactic bacteria of strain Mar 1–83, when swimming in an applied magnetic field, did not move as a homogeneous cell suspension, but aggregated in distinct wave-like structures, which remained stable during forward movement.
Abstract: Magnetotactic bacteria of strain Mar 1–83, when swimming in an applied magnetic field, did not move as a homogeneous cell suspension, but aggregated in distinct wave-like structures. The waves remained stable during forward movement. The number of cells per wave ranged from a few cells in permanent lateral contact to hundreds of bacteria moving visibly within a wave. Wave formation required a horizontal and vertical magnetic component. Electron microscopy indicated at least 3 distinct parallel chains of magnetosomes inside the bacterium. The cellular magnetic dipole moment was determined. Cell-to-cell magnetic interaction could be ruled out as the sole mechanism that induced wave formation and kept waves stable. Other mechanisms are discussed.
42 citations
TL;DR: Four species of magnetotactic bacteria have been detected in alkaline waters with pH 7.4-8.7 and each showed different patterns of movement, including two various types of magnetosomes, a chain-like arrangement and a scattered distributional pattern.
Abstract: Abstract Four species of magnetotactic bacteria have been detected in alkaline waters with pH 7.4-8.7. They were of coccoid to rod-like shape. Each of the species showed different patterns of movement. Two various types of magnetosomes, a chain-like arrangement and a scattered distributional pattern and a lateral polytrich flagellated type could be demonstrated with the coccoid species.
14 citations
TL;DR: In this paper, the formation of bands in magnetotactic bacteria has been suggested as analogous to instabilities in ferromagnetic fluids, and a tentative explanation for the formation is suggested.
11 citations
Patent•
18 Mar 1987
TL;DR: In order to collect the above-mentioned magnetic fine particles or separate the particles from magnetotactic bacteria gathered by culture fluid, the concentration by a micro-centrifuge is carried out and the bacterial walls are dissolved with a lysozyme solution as discussed by the authors.
Abstract: PURPOSE:Immobilized magnetic fine particles of a physiologically active substance, obtained by separating from magnetotactic bacteria, having a large surface area due to the small particle size and very large amount of the supported physiologically active substance. CONSTITUTION:The above-mentioned magnetic fine particles are separated from magnetotactic bacteria and can be used even in a state of either being covered with a coating film consisting mainly of a protein or free from the coating film. In general, the magnetic fine particles having the coating film has an advantage in that the harmony with the living body is good. In order to collect the above-mentioned magnetic fine particles or separate the particles from magnetotactic bacteria gathered by culture fluid, the concentration by a micro-centrifuge is carried out and the bacterial walls are dissolved with a lysozyme solution. The centrifugation may then be repeated. Examples of the kind of the physiologically active substance to be immobilized by the separated magnetic fine particles include enzymes, e.g. hydrolase or oxidoreductase, immunity-related substances, growth factors, nucleic acid-related substances, physiologically active substances derived from plants and other physiologically active substances.
Patent•
28 Jul 1987
TL;DR: In this article, the separation and recovery of magnetotactic bacteria from a liquid containing said bacteria in high purity at a high speed was carried out by placing the liquid containing magnetotactic bacteria in a high magnetic field, attracting and fixing the bacteria to a polar surface generating magnetic force line at high speed and releasing the fixed bacteria by eliminating the magnetic field.
Abstract: PURPOSE:To carry out the separation and recovery of magnetotactic bacteria from a liquid containing said bacteria in high purity at a high speed, by placing a liquid containing magnetotactic bacteria in a high magnetic field, attracting and fixing the magnetotactic bacteria to a polar surface generating magnetic force line at a high speed and releasing the fixed bacteria by eliminating the magnetic field. CONSTITUTION:In the 1st step, a process for contacting a stock liquid containing magnetotactic bacteria with a surface 2 generating magnetic force line of >=1,000 Gauss to effect the adsorption of the bacteria to the surface 2 and a process for cleaning the bacteria adsorbed to the surface 2 with a cleaning liquid 7 under the influence of the magnetic force line are repeated once or more. In the 2nd step, the surface 2 washed in the 1st step is made to contact with a desorption liquid 7 under a condition free from magnetic field to transfer the bacteria into the desorption liquid 7. Finally, the desorption liquid produced by the 2nd step is taken out of the system in the 3rd step. The magnetotactic bacteria can be separated by this process from the stock liquid containing said bacteria in high speed, recovery and purity with magnetic force.
Patent•
18 Mar 1987
TL;DR: In this article, a filtering means is used to separate magnetotactic bacteria living in seawater or fresh water from floating materials and readily and efficiently collect the bacteria, by using a special collecting tool of the magnetotactactic bacteria.
Abstract: PURPOSE:To separate magnetotactic bacteria living in seawater or fresh water from floating materials and readily and efficiently collect the bacteria, by using a special collecting tool of the magnetotactic bacteria CONSTITUTION:A filtering means 4, eg filter paper, having 2-3mum pores is mounted on the lower end of a container 1, having the closed top and an opening at the bottom and a side wall 2 and upper end wall 3 consisting of a plastic material and one or more magnets 5, eg samarium cobalt based magnets, are provided on the top of the upper end wall 3 S poles are fixed in the northern hemisphere and N poles are fixed in the southern hemisphere The resultant collecting tool 1 is then sunk on a deposit 8 in the bottom of seawater or fresh water Magnetotactic bacteria swimming along the lines of magnetic force are fixed by the magnetic force to facilitate the collection and the magnetotactic bacteria 6 are led through the filtering means 4 into the container 1, gathered and collected
Patent•
21 Feb 1987
TL;DR: In this article, a solution to be treated which contains mixed magnetotactic bacteria, minute organisms and solid materials is fed from a piping 11 to a pretreating device 2, and the resultant dispersion is then fed to a separator 4 having magnets (1A and (1B') at the top and bottom The magnetic poles are positioned to direct the magnetic pole to which the bacteria run to the upward direction.
Abstract: PURPOSE:To efficiently separate magnetotactic aquatic bacteria, by giving stimulation to a solution containing the magnetotactic aquatic bacteria, etc, leading the solution to a separator and applying a magnetic field thereto CONSTITUTION:A solution to be treated which contains mixed magnetotactic bacteria, minute organisms and solid materials is fed from a piping 11 to a pretreating device 2, and the bacteria are dispersed by stirring, etc The resultant dispersion is then fed to a separator 4 having magnets (1A) and (1A') at the top and bottom The magnetic poles are positioned to direct the magnetic pole to which the bacteria run to the upward direction The upper solution, in which the bacteria are concentrated, is mixed with a diluting solution in a pretreating device 3 in the second stage and further a magnetic field is applied thereto in a separator 5 having magnets (1B) and (1B') provided to run the bacteria in the upward direction The resultant solution in which the bacteria are concentrated is recovered from the upper part of the separator 5 Settled solid materials and residual solution are respectively taken out of the bottoms of the separators 4 and 5
Patent•
21 Dec 1987
TL;DR: In this paper, a magnetic substance, obtained by cultivating magnetotactic bacteria collected from ponds, lakes, etc, in a nutrient culture medium, having an extremely fine and uniform particle diameter as well as good purity and applicable as an additive for toners, is presented.
Abstract: PURPOSE:A magnetic substance, obtained by cultivating magnetotactic bacteria collected from ponds, lakes, etc, in a nutrient culture medium, having an extremely fine and uniform particle diameter as well as good purity and applicable as an additive for toners CONSTITUTION:Water containing magnetotactic bacteria is separated from sludge water collected from ponds using a magnet and an inorganic salt, vitamin, etc, are added to the resultant filtrate water to carry out cultivation in a culture medium Spiral magnetotactic bacteria Aquaspirillum magnetotacticum are isolated from the culture medium The resultant bacteria are then cultivated in a nutrient culture medium with preferably <=01wt% salt concentration at 60-75pH at about room temperature under slightly aerobic condition to give magnetic iron oxide The resultant magnetic iron oxide in an amount of preferably 40-90ptswt and antioffset agent in an amount of 05-8ptswt are blended with 100ptswt binding resin to give a blend, which is then melt kneaded, cooled and subjected to a method for pulverizing, classifying, etc, to afford the aimed magnetic toner