Magnetotactic bacteria

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

Characterization of Magnetosomes After Exposure to the Effect of the Sonication and Ultracentrifugation

Abstract: Magnetosomes are intracellular organelles of widespread aquatic microorganisms called Magnetotactic bacteria. At present they are under investigation especially in biomedical applications. This ability depends on the presence of intracellular magnetosomes which are composed of two parts: first, nanometer-sized magnetite (Fe3O4) or greigite (Fe 3S4) crystals (magnetosome crystal), depending on the bacterial species; and second, the bilayer membrane surrounding the crystal (magnetosome membrane). The magnetosomes were prepared by biomineralization process of magnetotactic bacteria Magnetospirillum Magnetotacticum sp. AMB-1. The isolated magnetosome chains (sample M) were centrifugated at speed of 100000 rpm for 4 hours (sample UM) and sonicated at power of 120 W for 3 hours (sample SM), respectively. The prepared suspensions were investigated with respect to morphological, structural and magnetic properties. The results from scanning electron microscopy showed that isolated chains of magnetosomes were partially broken to smaller ones after ultracentrifugation. On the other hand the application of the sonication process caused the formation of individual magnetosomes (unordered in chain). These results were confirmed by coercivity and magnetization saturation measurements.

Acting on nanoparticles embedded in magnetotactic bacteria to implement propulsion and steering for microrobots

Abstract: A MEMS structure based on standard CMOS process is presented. It consists in the fabrication of micro-reservoirs in which will be embedded magnetotactic bacteria (MTB) to form a propulsion system for a 550 mum x 650 mum fully autonomous micro- robot to be operated in an aqueous medium. Due to magnetotaxis inherent in each bacterium, the motility of the MTB can be exploited. Furthermore, a directional magnetic field is used to orient their swimming direction. This magnetic field is produced by micro-coils embedded in each micro-reservoir. The operational power of the microrobot is collected through four photovoltaic cells which are able to provide a current of 65 muA and a low voltage of 400 mV to drive the micro-coils. Due to the size of the microrobot, the integration of the MTB into the micro-reservoirs is a complicated task. Here, a method to facilitate the integration of the MTB into such micro-reservoirs is proposed, which consists in the use of an external magnet placed iteratively at different locations with respect to the microrobot in order to gather the MTB near the micro-reservoir aperture consequently near the magnetic field lines generated inside of the micro-coils.

Reply to Wang and Chen: An ancient origin of magnetotactic bacteria.

Abstract: Our recent paper (1) reports an ancient origin of magnetotactic bacteria (MTB) before or near the divergence between the phyla Nitrospirae and Proteobacteria, which has implications for the Archean geomagnetic field and paleoenvironment.

Restoration and Modification of Magnetosome Biosynthesis by Internal Gene Acquisition in a Magnetotactic Bacterium.

Abstract: Integration of a large-sized DNA fragment into a chromosome is an important strategy for characterization of cellular functions in microorganisms. Magnetotactic bacteria synthesize intracellular organelles comprising membrane-bound single crystalline magnetite, also referred to as magnetosomes. Magnetosomes have gained interest in both scientific and engineering sectors as they can be utilized as a material for biomedical and nanotechnological applications. Although genetic engineering of magnetosome biosynthesis mechanism has been investigated, the current method requires cumbersome gene preparation processes. Here, the chromosomal integration of a plasmid containing ≈27 magnetosome genes (≈26 kbp region) in a non-magnetic mutant of Magnetospirillum magneticum AMB-1 using a broad-host-range plasmid is shown. The genome sequencing of gene-complemented strains reveals the chromosomal integration of the plasmid with magnetosome genes at a specific site, most likely by catalysis of an endogenous transposase. Magnetosome production is successfully enhanced by integrating a variation of magnetosome gene operons in the chromosome. This chromosomal integration mechanism will allow the design of functional magnetosomes de novo and M. magneticum AMB-1 may be used as a chassis for the designed magnetosome production.

Magnetotactic Bacteria and Their Significance for P Systems and Nanoactuators

Abstract: In the framework of the dialog between P systems and Microbiology, in this paper we focus on the magnetotactic behavior of magnetotactic bacteria, namely the orientation along the Earth’s geomagnetic field lines. Magnetic properties and magnetotactic behavior could be used to obtained microand nanoactuators for the desired distribution at nanometer level of either intact magnetotactic bacteria or isolated intact magnetosomes with significant potential application in the construction of magnetic logic gates. Furthermore, (precise) distribution of intact magnetotactic bacteria or isolated intact magnetosomes by carefully using rather strong external magnetic fields could be described by P systems as a discontinuous process, whose potential for nanoactuators and magnetic microchips is increasing in evidence.