环境条件对磁螺菌生长的影响

目的了解碳源种类及浓度、氧、还原剂等条件对磁螺菌（Magnetospirillum gryphiswaldense）生长的影响；建立深层培养磁螺菌及磁小体的技术。方法在60ml血清瓶中，将供试菌株在不同种类和浓度的碳源培养基，不同氧浓度等条件下培养，测定OD600nm；在5L自动控制发酵罐（L．E．Marubishi Co．Tokyo，Japan）中，控制pH、温度及转速分别为7．2、30℃、400r／min，通气量为1．0L／min-1．2L／min，氧浓度为0．5％-0．7％的条件下，以乙酸钠-苹果酸培养基和乳酸钠培养基深层培养供试菌株，测定OD60nm.用高效液相色谱等分析培养过程中碳氮源变化规律；用电子显微镜观察磁小体的合成。结果碳源的种类及浓度是影响该菌生长和磁小体合成的重要因素之一；在乙酸钠一苹果酸培养基和乳酸钠培养基中深层培养25h的细胞密度分别为0．7和1．7OD600nm.结论乳酸钠培养基是适合于磁螺菌快速生长的最佳培养基。建立了深层培养磁螺菌及磁小体的技术和方法，该方法的建立对于大量获得细菌磁小体而进行应用开发具有重要意义。

Effect of conditions on growth of Magnetospirillum gryphiswaldense

[Objective] Understand the effect of the kinds and concentrations of carbon source, O2 and reducing agent etc on growth of M. gryphiswaldense. Set up a submerged culture technique for growth of cells and formation of magnetosomes of M. gryphiswaldense. [Methods] In stopped 60 mL bottle, the cells of M. gryphiswaldense were cultivated in various kinds and concentrations of carbon source medium and under conditions of various concentrations of O2 etc. The optical density (OD600 nm) of cells was assayed. In a 5 L auto-controlled fermentor, the cells of this organism were cultivated in NaAc-malic acid medium and Na-Lactate medium. The pH, temperature and stirring rate were controlled at 7.2, 30℃ and 400 r/min respectively. The rate of gas flow was set to 1.0～1.2 liters per min and the concentration of O2 in gas flow were controlled at a constant level of 0.5% to 0.7 %. The change of C and N source during whole period of submerged culture were assayed by HPLC etc. The formation of magnetosomes was observed by transmission electron microscope. [ Results ] The kinds and concentrations of carbon source were one of key factors for the growth of this organism and formation of magnetosomes. The optical density (OD600 nm) of cells of submerged culture in NaAc-Malate medium and sodium lactate medium were 0.7 and 1.7 respectively within 25 hours. [Conclusion] The optimum medium for fast growth of this organism was sodium lactate medium. A submerged culture technique for the growth of cells and formation of magnetosomes of M. gryphiswaldense was set up,which is important for obtained enough magnetosomes and its application.