摘要
南京城郊一淡水池塘污泥中存在一种弧形趋磁细菌NMV—1,在地磁场作用下一致向北游动,细胞可连接成链状,有2～13个菌体,长达2～10μm,透射电子显微镜(TEM)观察表明每个细胞内含11～15颗磁小体,呈长方体,沿菌体长轴排列成链状,磁小体尺度为:长120nm,宽80nm,处在稳定的单磁畴晶体范围内.能谱分析仪显示该菌磁小体的元素组成为铁(Fe),由晶体衍射分析表明磁小体为单晶结构.
Magnetotaxis in bacteria is the result of a permanent magnetic dipole moment that causes a cell to be oriented in the earth's geomagnetic field as it swims. The magnetic dipole moment is caused by the presence of magnetosomes, intracellular, iron rich, membrane enclosed magnetic particles. The mineral phases of the magnetosomes are of two general types: iron oxides and iron sulfides. Iron oxide type magnetosomes contain particles of the ferrimagnetic mineral magnetite (Fe 3O 4) while the iron sulfide type contains ferrimagnetic greigite (Fe 3S 4), greigite and non magnetic pyrite (FeS 2), or possibly ferrimagnetic pyrrhotite (Fe 7S 8). Regardless of their composition, the crystalline particles in magnetosomes have a narrow size range: approximately 25 to 120 nm. Magnetite crystals in this size range are single magnetic domains and confer a permanent magnetic dipole moment on the cell. The morphology of the particles in the bacterial magnetosomes appears to be species specific. Morphologies of magnetite crystals in different species of magnetotactic bacteria include cubo octahedra, parallelepipedal, and tooth or bullet shaped. Morphologies of greigite particles include cubo octahedra and rectangular prismatic. The greigite pyrite particles are generally pleomorphic with no consistent crystalline morphology. Bacterial production of magnetite makes an important contribution to iron biomineralizatiion and remanent magnetization of sediments. A strain G Magnetic vibrio (NMV 1) was present in surface sediments collected from the pool in Nanjing suburbs. They orientated and navigated along geomagnetic field lines. Cells frequently formed the chains of up to thirteen cells, 2～10μm in length. Transmission electron micrographs show that the NMV 1 with chains of 11～15 magnetosomes. The chains of magnetosomes were 1.3μm long, the individual mature magnetosomes as 120nm in length and 80nm in width and cuboidal in shape. The size of all the well formed crystals fall within the calculat
出处
《南京大学学报（自然科学版）》
CAS
CSCD
1999年第6期745-749,共5页
Journal of Nanjing University（Natural Science）
