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Magnetotactic bacteria

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


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TL;DR: This work demonstrates the control of magnetotactic bacteria through the application of magnetic field gradients with real-time visualization by integrating a pair of macroscale Helmholtz coils and lithographically fabricated nanoscale islands composed of permalloy.
Abstract: Herein, we demonstrate the control of magnetotactic bacteria through the application of magnetic field gradients with real-time visualization. We accomplish this control by integrating a pair of macroscale Helmholtz coils and lithographically fabricated nanoscale islands composed of permalloy (Ni₈₀Fe₂₀). This system enabled us to guide and steer amphitrichous Magnetospirillum magneticum strain AMB-1 to specific location via magnetic islands. The geometries of the islands allowed us to have control over the specific magnetic field gradients on the bacteria. We estimate that magnetotactic bacteria located less than 1 μm from the edge of a diamond shaped island experience a maximum force of approximately 34 pN, which engages the bacteria without trapping them. Our system could be useful for a variety of applications including magnetic fabrication, self-assembly, and probing the sensing apparatus of magnetotactic bacteria.

9 citations

Journal ArticleDOI
TL;DR: A summary of nano‐ and microtechnologies that are developed for purposes such as MTB sorting, genetic engineering, and motility assays is provided and the use of existing platforms that can be adapted for large‐scale MTB processing including microfluidic bioreactors is described.
Abstract: Author(s): Tay, A; McCausland, H; Komeili, A; Di Carlo, D | Abstract: Magnetotactic bacteria (MTB) naturally synthesize magnetic nanoparticles that are wrapped in lipid membranes. These membrane-bound particles, which are known as magnetosomes, are characterized by their narrow size distribution, high colloidal stability, and homogenous magnetic properties. These characteristics of magnetosomes confer them with significant value as materials for biomedical and industrial applications. MTB are also a model system to study key biological questions relating to formation of bacterial organelles, metal homeostasis, biomineralization, and magnetoaerotaxis. The similar size scale of nano and microfluidic systems to MTB and ease of coupling to local magnetic fields make them especially useful to study and analyze MTB. In this Review, a summary of nano- and microtechnologies that are developed for purposes such as MTB sorting, genetic engineering, and motility assays is provided. The use of existing platforms that can be adapted for large-scale MTB processing including microfluidic bioreactors is also described. As this is a relatively new field, future synergistic research directions coupling MTB, and nano- and microfluidics are also suggested. It is hoped that this Review could start to bridge scientific communities and jump-start new ideas in MTB research that can be made possible with nano- and microfluidic technologies.

9 citations

Journal ArticleDOI
TL;DR: In this paper, four samples containing ultrafine and fine-grained magnetite of magnetoferritins and magnetotactic bacteria cells were magnetically characterized at both room and low temperatures.
Abstract: Four samples containing ultrafine- and fine-grained magnetite of magnetoferritins and magnetotactic bacteria cells were magnetically characterized at both room and low temperatures. Transmission electron microscopy analysis showed that the biometrically synthesized magnetoferritins (M-HFn) have magnetite cores with a mean size of 5.3 ± 1.2 nm inside protein shells, while Magnetospirillum gryphiswaldense MSR-1 cell produced intracellular magnetosome magnetites have a mean size of 29.6 ± 7.6 nm, arranged in a single chain. A pure M-HFn sample (M1), MSR-1 whole cell sample (M4) and two samples (M2, M3) mixing M-HFn with MSR-1 whole cells in different weight percentages were measured, including hysteresis, temperature dependency of magnetization and remanence and frequency dependence of AC susceptibility at low temperature. At room temperature, the ultrafine-grained magnetite core of M-HFn of M1 sample has a typical superparamagnetic (SP) behavior. The chain-arranged magnetosome magnetite of MSR-1 cells of M4 sample shows a stable single-domain (SD) state. At low temperature, the M2 sample with ~ 16 wt% SD magnetosome magnetite and the M3 sample with ~ 43 wt% SD magnetosome magnetite behave somewhat similar to the M1 (pure M-HFn), due to the SP component from M-HFn magnetite. With the dominance of SP magnetite in samples M1, M2, and M3, the coercivity and saturation remanence decrease significantly as temperature increasing from 5 to 20 K. Of note, the magnetization and frequency dependence of AC susceptibility at low temperature are sensitive to SP magnetites in measured samples. The magnetosome magnetite produced by MSR-1 has a Verwey transition temperature at around 100 K, which is consistent with previous observations on magnetotactic bacteria. This study provides useful clues for identification of SP and SD magnetite in sediments, as well as related potential biomedical and biomagnetic applications.

9 citations

Journal ArticleDOI
TL;DR: This review summarizes various apparatus, setups and media formulations designed for obtaining axenic MTB strains since their discovery by Richard Blakemore in 1975.
Abstract: Magnetotactic bacteria (MTB), a diverse group of ubiquitously occurring Gram negative procaryotes are currently the subject of interdisciplinary research. The unique trait of synthesis and biomineralization of nano-sized magnetic particles in the ideal range of 30 to 120 nm makes them suitable for biomedical and biotechnological applications. However, research in this field has not reached a commercial scale as these bacteria are notoriously difficult to culture. Culturing this metabolically versatile group of bacteria on defined medium is still a challenging task even though a few MTB strains have been isolated and purified in the past. Scientists worldwide are developing different strategies to trap MTB under artificial laboratory conditions. This review summarizes various apparatus, setups and media formulations designed for obtaining axenic MTB strains since their discovery by Richard Blakemore in 1975.

9 citations

Journal ArticleDOI
TL;DR: The benefit of using magnetotactic bacteria as cellular chassis to design and build sensitive magnetic bacterial biosensors is investigated and the successful preservation of the magnetic bacterium biosensor by freeze-drying is demonstrated.
Abstract: According to the World Health Organization, arsenic is the water contaminant that affects the largest number of people worldwide. To limit its impact on the population, inexpensive, quick, and easy-to-use systems of detection are required. One promising solution could be the use of whole-cell biosensors, which have been extensively studied and could meet all these criteria even though they often lack sensitivity. Here, we investigated the benefit of using magnetotactic bacteria as cellular chassis to design and build sensitive magnetic bacterial biosensors. Promoters potentially inducible by arsenic were first identified in silico within the genomes of two magnetotactic bacteria strains, Magnetospirillum magneticum AMB-1 and Magnetospirillum gryphiswaldense MSR-1. The ArsR-dependent regulation was confirmed by reverse transcription-PCR experiments. Biosensors built by transcriptional fusion between the arsenic-inducible promoters and the bacterial luciferase luxCDABE operon gave an element-specific response in 30 min with an arsenite detection limit of 0.5 μM. After magnetic concentration, we improved the sensitivity of the biosensor by a factor of 50 to reach 10 nM, more than 1 order of magnitude below the recommended guidelines for arsenic in drinking water (0.13 μM). Finally, we demonstrated the successful preservation of the magnetic bacterium biosensors by freeze-drying. IMPORTANCE Whole-cell biosensors based on reporter genes can be designed for heavy metal detection but often require the optimization of their sensitivity and specific adaptations for practical use in the field. Magnetotactic bacteria as cellular hosts for biosensors are interesting models, as their intrinsic magnetism permits them to be easily concentrated and entrapped to increase the arsenic-response signal. This paves the way for the development of sensitive and immobilized whole-cell biosensors tailored for use in the field.

9 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202339
202288
202137
202061
201950
201873