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 (OD(subscript 600 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 mm 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 (OD(subscript 600nm)) 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.