Magnetotactic bacteria

About: Magnetotactic bacteria is a research topic. Over the lifetime, 1118 publications have been published within this topic receiving 43741 citations.

Mass culture of magnetic bacteria and their application to flow type immunoassays

Abstract: Isolated helical magnetotactic bacteria were cultured in a medium containing succinate, nitrate, and ferric malate as carbon, nitrogen, and iron sources, respectively The magnetotactic bacteria could grow aerobically The cells which grew aerobically had oxidase activity An initial inoculum of 10/sup 5/ cells/ml was used Stationary phase was reached 14*10/sup 9/ cells/ml after 4-5 days growth When the cells were disrupted using ultrasonication, 26-mg bacterial magnetites were obtained from a 1-l culture of magnetotactic bacteria The detection of mouse IgG was carried out using FITC (fluorescein-isothiocyanate) conjugated anti-mouse-IgG immobilized on bacterial magnetites and a flow injection system with a fluorescence spectrophotometer Relative fluorescence intensity correlated linearly with the concentration of mouse IgG in the range 05-100 ng/ml, and the measurements were established within 2 min using this system >

Deletion of a fur-Like Gene Affects Iron Homeostasis and Magnetosome Formation in Magnetospirillum gryphiswaldense

Abstract: Magnetotactic bacteria synthesize specific organelles, the magnetosomes, which are membrane-enveloped crystals of the magnetic mineral magnetite (Fe3O4) The biomineralization of magnetite involves the uptake and intracellular accumulation of large amounts of iron However, it is not clear how iron uptake and biomineralization are regulated and balanced with the biochemical iron requirement and intracellular homeostasis In this study, we identified and analyzed a homologue of the ferric uptake regulator Fur in Magnetospirillum gryphiswaldense, which was able to complement a fur mutant of Escherichia coli A fur deletion mutant of M gryphiswaldense biomineralized fewer and slightly smaller magnetite crystals than did the wild type Although the total cellular iron accumulation of the mutant was decreased due to reduced magnetite biomineralization, it exhibited an increased level of free intracellular iron, which was bound mostly to a ferritin-like metabolite that was found significantly increased in Mossbauer spectra of the mutant Compared to that of the wild type, growth of the fur mutant was impaired in the presence of paraquat and under aerobic conditions Using a Fur titration assay and proteomic analysis, we identified constituents of the Fur regulon Whereas the expression of most known magnetosome genes was unaffected in the fur mutant, we identified 14 proteins whose expression was altered between the mutant and the wild type, including five proteins whose genes constitute putative iron uptake systems Our data demonstrate that Fur is a regulator involved in global iron homeostasis, which also affects magnetite biomineralization, probably by balancing the competing demands for biochemical iron supply and magnetite biomineralization

Newly isolated but uncultivated magnetotactic bacterium of the phylum Nitrospirae from Beijing, China.

Abstract: Magnetotactic bacteria (MTB) in the phylum Nitrospirae synthesize up to hundreds of intracellular bullet-shaped magnetite magnetosomes. In the present study, a watermelon-shaped magnetotactic bacterium (designated MWB-1) from Lake Beihai in Beijing, China, was characterized. This uncultivated microbe was identified as a member of the phylum Nitrospirae and represents a novel phylogenetic lineage with ≥6% 16S rRNA gene sequence divergence from all currently described MTB. MWB-1 contained 200 to 300 intracellular bullet-shaped magnetite magnetosomes and showed a helical swimming trajectory under homogeneous magnetic fields; its magnetotactic velocity decreased with increasing field strength, and vice versa. A robust phylogenetic framework for MWB-1 and all currently known MTB in the phylum Nitrospirae was constructed utilizing maximum-likelihood and Bayesian algorithms, which yielded strong evidence that the Nitrospirae MTB could be divided into four well-supported groups. Considering its population densities in sediment and its high numbers of magnetosomes, MWB-1 was estimated to account for more than 10% of the natural remanent magnetization of the surface sediment. Taken together, the results of this study suggest that MTB in the phylum Nitrospirae are more diverse than previously realized and can make important contributions to the sedimentary magnetization in particular environments.