Biomineralization,crystallography and magnetic properties of bullet-shaped magnetite magnetosomes in giant rod magnetotactic bacteria
作者单位：France-China Bio-Mineralization and Nano-Structures LaboratoryBeijing 100029China Department of Earth and Environmental ScienceLudwig-Maximilians-UniversitatD-80333 MunichGermany
会议名称：《中国科学院地质与地球物理研究所第十届(2010年度)学术年会》
会议日期：2011年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：supported by NSFC grants(40821091) the CAS/SAFEA International Partnership Program for Creative Research Teams
关 键 词：magnetotactic bacteria bullet-shaped magnetite magnetosome biomineralization crystallography sedimentary magnetism
摘 要：Magnetosomes produced by magnetotactic bacteria are of great interest for understanding bacterial biomineralization along with sedimentary magnetism and environmental *** of the most intriguing species,Magnetobacterium bavaricum can synthesize hundreds of bullet-shaped magnetite magnetosomes per cell,which contribute significantly to magnetic properties of ***,the biomineralization mechanism and magnetic properties of such magnetosomes remain *** this paper,we have conducted a comprehensive study of the crystallography and magnetic properties of bullet-shaped magnetosomes formed by uncultivated giant rod magnetotactic bacteria(referred to as MYR-1), recently discovered in Lake Miyun(Beijing,China).Transmission electron microscopy observations reveal that each MYR-1 cell contains hundreds of bullet-shaped magnetite magnetosomes,which are arranged into 3-5 braid-like bundles of *** formation of the bullet-shaped magnetosomes can be divided into two stages:initial isotropic growth(up to～20 nm)followed by elongation along the[100]direction,which is unusual compared with the expected[111]magnetic easy *** the[100]orientation is the hard axis of the face-centered cubic magnetite,the shape anisotropy of bullet-shaped magnetosomes and intra-bundle magnetostatic interactions confine the magnetization direction of the chain along the long axis of the cell/*** to each bundle of magnetosome chains effectively behaving as an elongated single domain particle,the MYR-1 cells show high coercivity,weak intra-bundle magnetostatic interaction,and high 6-ratio. These results provide new insights into the biomineralization process and magnetic properties of bullet-shaped magnetite magnetosomes.