The Study On Isolation And Cultivation Of Magnetotactic Bacteria And Purification Of Magnetosomes

Many kinds of magnetotactic bacteria were enriched from Iron Ore soil for the first time, and a microaerobic magnetotactic bacterium strain TK-2 was isolated in pure culture. TK-2 were generally vibrioid,sometimes helical cells. TK-2 was the same as the reported firstly magnetotactic bacteria, Aquaspirillum magnetotacticum MS-1 in some biophysiological and biochemical characteristics,but TK-2 and MS-1 were different in morphology,part biophysiological and biochemical characteristics and habitats. The homology between TK-2 and Herbaspirillum sp was 98% in the sequence of 16S rDNA. Therefore TK-2 was considered as a new species with magnetic characteristic in Herbaspirillum, and named as Herbaspirillum sp.TK-2.The magnetosomes about 50 nm from TK-2 was irregular polygon. The optimum culture medium of magnetotactic bacteria TK-2 was consisting of (per 1000 ml of medium): 1.16 g of NaAc; 0.45 g of NH4Cl; 50μg of vitB12; 2mg of resazurin;100μmol/L ferric quinate solution;1.16 mmol/L potassium phosphate buffer(pH6.7); 1mL of vitamin elixir(10×); 1mL of mineral elixir(10×). In the recycled culturing system about 0.867g of dry cells was yielded per liter of culture. The purified magnetosomes were obtained when TK-2 cells were lysed indirectly by SDS. Nearly 90% of the magnetosomes was enveloped with membrane and kept the magnetism. The X-ray energy spectrum analysis showed the main elements of magnetosomes were C,K,Fe,Mg,P,Ca,Si,Cl,Al,S,Mn,O, and the main magnetic component of the magnetosomes was iron oxide.