Magnetotactic Bacteria - A Natural Architecture Leading from Structure to Possible Applications
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1188-LL08-01
Magnetotactic Bacteria – A Natural Architecture Leading from Structure to Possible Applications K. Yu-Zhang1, K.-L. Zhu2, T. Xiao2 and L.-F. Wu3 1
Laboratoire de Microscopies et d’Etude de Nanostructures (LMEN), Université de Reims, France. 2 Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China 3 Laboratoire de Chimie Bactérienne, UPR9043, CNRS, Marseille, France
ABSTRACT Magnetotactic bacteria are aquatic micro-organisms which have the specific capacity to navigate along the lines of the earth’s magnetic field. This property is related to the formation of chains of magnetic crystals called magnetosomes. All magnetotactic bacteria synthesize nanosized intracellular magnetosomes that are surrounded by ultra-thin bio-membranes. The magnetosome chains serve as compass for navigation of the magnetotactic bacteria, and the cell flagella are considered as the mechanism for propelling the bacteria forward. This presentation describes various functions of the architectured structure of magnetotactic bacteria as well as their possible applications in biotechnology. . INTRODUCTION Efficient design in natural systems can be considered in terms of the relationship between form or detailed structure and function just as there is a relationship between the engineer’s blueprint and the functioning of a complex structure such as a large building [1]. This approach to the architecture and design of natural systems is reflected in a number of classic texts. A striking example of that is a natural organism (aquatic prokaryote), which builds a machine (a chain of magnetic crystals named magnetosomes) directly within its own body. The structure of these tiny bacteria, inhabitants of the first rung on the traditional ladder of life, can illustrate fascinating features within a few microns that some organisms require meters to express. It was in 1975 that University of New Hampshire microbiologist R. P. Blakemore first discovered this special kind of bacteria in sediments near Woods Hole, Massachusetts (USA) [2], although in a much earlier internal report (1963) the “magnetosensitive bacteria” had been described by S. Bellini at the Institute of Microbiology, University of Pavia (Italy) [3-5]. These bacteria align themselves and migrate in preferred direction along the earth’s magnetic field lines, thus the name magnetotactic bacteria (MTB). It is well known that such property of MTB is related to the formation of chains of magnetosomes within the cell. Magnetosomes, the single crystalline magnetic particles of 30-120 nm in size, are usually made of ferrimagnetic magnetite (Fe3O4, spinel structure, Fd3m space group and lattice parameter a = 0.839 nm), and sometimes though more rarely of greigite (Fe3S4, spinel structure with lattice parameter a = 0.988 nm) [6].
If the inorganic magnetosome chains serve as the compass for navigation of magnetotactic bacteria, the organic cell flagella are normally considered as the mechanisms for propelling the b
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