We have studied the dynamic behavior of nanoparticles in ferrofluids consisting of single-domain, biogenic magnetite (Fe(3)O(4)) isolated from Magnetospirillum magnetotacticum (MS-1). Although dipolar chains form in magnetic colloids in zero applied field, when dried upon substrates, the solvent front disorders nanoparticle aggregation. Using avidin-biotin functionalization of the particles and...

Magnetotactic bacteria (MTB), Magnetospirillum magnetotacticum (MS-1) were successfully grown in modified magnetic spirillum growth medium (MSGM) at normal laboratory environment. About five-time increase in the bacterial yield was achieved in the modified MSGM medium without compromising their magnetosomes properties. Transmission electron and scanning electron microscopy (TEM & SEM) were used...

Magnetic particles have been studied with much interest with reference to many engineering applications. Much effort has been devoted to the preparation of nano-sized magnetite particles with well-controlled size and shape. Magnetic bacteria synthesize uniform and nano-sized magnetite particles enveloped by organic lipid membranes. This review discusses recent advances in bacterial magnetite pa...

Bacterial magnetosomes are intracellular compartments that house highly ordered magnetite crystals. By using Magnetospirillum sp. AMB-1 as a model system, we show that magnetosome vesicles exist in the absence of magnetite, biomineralization of magnetite proceeds simultaneously in multiple vesicles, and biomineralization proceeds from the same location in each vesicle. The magnetosome-associate...

The mechanism of how magnetotactic bacteria navigate along the magnetic field has been a puzzle. Two main models disagree on whether the magnetotactic behavior results from passive alignment with the magnetic field or active sensing of the magnetic force. Here, we quantitatively studied the swimming patterns of Magnetospirillum magneticum AMB-1 cells to understand the origin of their magnetotac...

Siderophore production by the magnetic bacterium Magnetospirillum magneticum AMB-1 is elicited by sufficient iron rather than by iron starvation. In order to clarify this unusual pattern, siderophore production was monitored in parallel to iron assimilation using the chrome azurol sulfonate assay and the ferrozine method respectively. Iron concentration lowered approximately five times less tha...