Research About The Biomineralization Of Magnetotactic Bacteria And The Extraction Of Magnetosomes

Magnetotactic bacterium is a kind of bacterium with the capability of swimming along geomagnetic field lines. The most distinguished characteristic of the bacteria in common is capable of synthesizing specific intracellular structures, magnetosomes, which are chain-linked and membrane-enveloped crystals of magnetic iron oxide or iron sulfide. CoMPared to magnetic nanoparticals synthesized by chemical method, magnetosome particals derived from magnetotactic bacteria have a number of potential advantages. Magnetosomes display narrow size distributions and uniform morphologies. Researchers from several laboratories have made significant progress in elucidating the ecology, screening, phylogenesis, physiology and biotechnologieal applications of magnetic bacteria. In this work, a novel combination of organic solvent and supercritical CO2method (OS-ScCO2) was used to extract biomineralized magnetosomes from magnetotactic bacteria for the first time. The combination role of organic solvent and scCO2was used to remove the cytoplasmic membrane of magnetotactic bacteria and to preserve the magnetosome membrane at control conditions. Magnetosomes extracted by OS-scCO2are proved with the features of small particle diameter, homogeneous distribution, high stability, no residual organic solvent and unique magnetic properties. It was shown that the extracted magnetosomes possess the characteristic of high saturation magnetization and superparamagnetic. Then the biomineralization of magnetotactic bacteria was studied. When the cobalt quinate and zinc quinate were added in the medium respectively, the magnetic properties of magnetotactic bacteria and magnetosomes would changed greatly. The magnetosomes had a high saturation magnetization of the zinc-doped and a high coercive field of the cobalt-doped. When the zinc quinate is15μM, the magnetization of magnetotacitc bacteria is37.3emu/g, which is maximal. With the increase of zinc quinate, the growth of magnetotactic bacteria is inhibited. These findings provide an important advance in designing biologically synthesized nanoparticles with useful highly tuned magnetic properties.