Magnetosomes: Membrane-bound prokaryotic organelles of magnetotactic bacteria that contain chains of MAGNETITE crystals which orient the bacteria to geomagnetic fields.Magnetospirillum: A genus of microaerophilic, gram-negative bacteria that forms crystals of the mineral magnetite in special organelles called MAGNETOSOMES.Ferrosoferric Oxide: Iron (II,III) oxide (Fe3O4). It is a black ore of IRON that forms opaque crystals and exerts strong magnetism.Magnetics: The study of MAGNETIC PHENOMENA.Sodium Lactate: The sodium salt of racemic or inactive lactic acid. It is a hygroscopic agent used intravenously as a systemic and urinary alkalizer.Holography: The recording of images in three-dimensional form on a photographic film by exposing it to a laser beam reflected from the object under study.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Organelles: Specific particles of membrane-bound organized living substances present in eukaryotic cells, such as the MITOCHONDRIA; the GOLGI APPARATUS; ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.Bacterial Proteins: Proteins found in any species of bacterium.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.