【摘要】 目的　了解磁螺菌 (Magnetospirillumgryphiswaldense)细胞合成磁小体的过程 ,研究磁小体的提取和纯化方法。方法　供试菌株在 5L自动发酵罐中微氧培养并定时取样电镜观察 ,用超声波破碎、蔗糖密度梯度离心、多次超声波打散和缓冲液洗涤等方法获得纯化的磁小体 ,用电镜和能谱对其纯度进行检测。结果　培养 8h的细胞已有小磁粒合成且分散于细胞膜内侧 ,培养 4 0h后的磁小体沿细胞长轴呈链状排列于细胞中央 ;获得具有完整外膜包被的高度纯化的磁小体 ,收率为 4 0mg(干重 ) /L培养液。 结论　磁小体合成的位点可能分散于细胞质膜内侧的不同部位 ;建立了磁小体纯化和纯度检测的方法 ,该方法对于磁小体的应用研究具有重要意义。更多还原

【Abstract】 Objective:Study the formation of the magentosomes in Magnetospirillum gryphiswaldense cells. Investigate the methods for extracting and purifying of the bacterial magnetosomes.Methods:The cells of M. gryphiswaldense were cultivated in 5 L auto-control fermentor and were sampled at different time for electron microscopic observation. The cells were harvested by centrifugation and disrupted by ultrasonication. The magnetosomes were purified by sucrose density gradient centrifugation and washed at least 15 times with HEPES buffer. The purity of the magnetosomes were detected by transmission electron microscope and energy spectrometer.Results:The magnetosomes started to form after 8 hours cultivation in 5L auto-control fermentor,and dispersed on the inner side of cytoplasmic memebrane. About 25～30 magnetosomes were arranged in chains along the long axis of cells after 40 hours. About 40 mg (dry weight) of pure magnetosomes per liter cultural solution was obtained. The obtained magnetosomes are 25～55 nm in diameter and enveloped with outer membrane.Conclusion:The magnetosome formation perhaps take place in different sites which are in the inner side of cytoplasmic membrane. The methods for obtaining magnetosomes with high purity was established, which is important for the application of the magnetosome.更多还原