Magnetotactic bacteria

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

Culture method of magnetotactic bacteria AMB-1

Abstract: The invention discloses a culture method of magnetotactic bacteria AMB-1. The culture method comprises the following steps that 1, activating bacteria; 2, obtaining first enlarged culture bacteria; 3, obtaining second enlarged culture bacteria; 4, obtaining third enlarged culture bacteria; 5, taking a proper amount of the third enlarged culture bacteria liquid obtained in the step 4 to be inoculated into a sterile fluid nutrient medium 1653 MSMG, and conducting fermenter culture; 6, conducting centrifugation to collect the bacteria in the materials obtained in the step 5, and conducting ultrasonication washing, purification and freeze drying to obtain magnetosomes. According to the method, the aim that the AMB-1 bacteria density and the magnetosome yield are greatly improved though fermenter culture can be achieved under the conditions that only the addition amount of an iron source is changed and pH is controlled to be constant.

U-turn trajectories of magnetotactic cocci allow the study of the correlation between their magnetic moment, volume and velocity

Abstract: Magnetotactic bacteria are microorganisms that present intracellular chains of magnetic nanoparticles, the magnetosome chain. A challenge in the study of magnetotactic bacteria is the measurement of the magnetic moment associated with the magnetosome chain. Several techniques have been used to estimate the average magnetic moment of a population of magnetotactic bacteria, and others permit the measurement of the magnetic moment of individual bacteria. The U-turn technique allows the measurement of the individual magnetic moment and other parameters associated with the movement and magnetotaxis, such as the velocity and the orientation angle of the trajectory relative to the applied magnetic field. The aim of the present paper is to use the U-turn technique in a population of uncultured magnetotactic cocci to measure the magnetic moment, the volume, orientation angle and velocity for the same individuals. Our results showed that the magnetic moment is distributed in a log-normal distribution, with a mean value of 8.2 × 10–15 Am2 and median of 5.4 × 10–15 Am2. An estimate of the average magnetic moment using the average value of the orientation cosine produces a value similar to the median of the distribution and to the average magnetic moment obtained using transmission electron microscopy. A strong positive correlation is observed between the magnetic moment and the volume. There is no correlation between the magnetic moment and the orientation cosine and between the magnetic moment and the velocity. Those null correlations can be explained by our current understanding of magnetotaxis.

Device for high-efficient separation of magnetotactic bacteria in high gradient magnetic field

Abstract: The invention discloses a device for high-efficient separation of magnetotactic bacteria in a high gradient magnetic field, which comprises a container for accommodating liquid containing magnetotactic bacteria, and is characterized in that the container is disposed in a solenoid; the solenoid is connected with a low frequency power supply; a steel wool with magnetic conductibility is disposed in the container. The device of the invention has a high magnetic field gradient; the magnetic field force applied to the magnetotactic bacteria is hundred times higher than that applied by a permanent magnet, and thus the magnetotactic bacteria can be captured easily, and are not washed away with solutions. The adsorption efficiency is improved greatly. The high gradient magnetic field can be removed at any time by turning off the electromagnetic field, and thus the magnetotactic bacteria are easily washed off from the steel wool, realizing the purpose of separation or recovery. The device is low in technical cost, high in efficiency, and free of secondary pollution.

The Effect of Sonication on Acoustic Properties of Biogenic Ferroparticle Suspension

Abstract: Superparamagnetic iron oxide nanoparticles (SPION) synthesised chemically usually need the modification of the particle surface. Other natural sources of magnetic particles are various magnetotactic bacteria. Magnetosomes isolated from magnetotactic bacteria are organelles consisting of magnetite (Fe$_3$O$_4$) or greigite (Fe$_3$S$_4$) crystals enclosed by a biological membrane. Magnetotactic bacteria produce their magnetic particles in chains. The process of isolation of magnetosome chains from the body of bacteria consists of a series of cycles of centrifugation and magnetic decantation. Using a high-energy ultrasound it is possible to break the magnetosome chains into individual nanoparticles – magnetosomes. This study presents the effect of sonication of magnetosome suspension on their acoustic properties, that is speed and attenuation of the sound. Acoustic propagation parameters are measured using ultrasonic spectroscopy based on FFT spectral analysis of the received pulses. The speed and attenuation of ultrasonic waves in magnetosome suspensions are analysed as a function of frequency, temperature, magnetic field intensity, and the angle between the direction of the wave and the direction of the field.

Molecular Imaging with Genetically Programmed Nanoparticles

Abstract: Nanoparticle research has greatly benefitted medical imaging platforms by generating new signals, enhancing detection sensitivity, and expanding both clinical and preclinical applications. For magnetic resonance imaging, the fabrication of superparamagnetic iron oxide nanoparticles has provided a means of detecting cells and has paved the way for magnetic particle imaging. As the field of molecular imaging grows and enables the tracking of cells and their molecular activities so does the possibility of tracking genetically programmed biomarkers. This chapter discusses the advantages and challenges of gene-based contrast, using the bacterial magnetosome model to highlight the requirements of in vivo iron biomineralization and reporter gene expression for magnetic resonance signal detection. New information about magnetosome protein interactions in non-magnetic mammalian cells is considered in the light of design and application(s) of a rudimentary magnetosome-like nanoparticle for molecular imaging. Central to this is the hypothesis that a magnetosome root structure is defined by essential magnetosome genes, whose expression positions the biomineral in a given membrane compartment, in any cell type. The use of synthetic biology for programming multi-component structures not only broadens the scope of reporter gene expression for molecular MRI but also facilitates the tracking of cell therapies.