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Magnetotactic bacteria (MTB) play an important role in Earth's biogeochemical cycles by transporting minerals in aquatic ecosystems, and have shown promise for controlled transport of microscale objects in flow conditions. However, how MTB traverse complex flow environments is not clear. Here, using microfluidics and high-speed imaging, it is revealed that magnetotaxis enables directed motion of Magnetospirillum magneticum over long distances in flow velocities ranging from 2 to 1260 µm s , corresponding to shear rates ranging from 0.2 to 142 s -a range relevant to both aquatic environments and biomedical applications. The ability of MTB to overcome a current is influenced by the flow, the magnetic field, and their relative orientation. MTB can overcome 2.3-fold higher flow velocities when directed to swim perpendicular to the flow as compared to upstream, as the latter orientation induces higher drag. The results indicate a threshold drag of 9.5 pN, corresponding to a flow velocity of 550 µm s , where magnetotaxis enables MTB to overcome counterdirectional flow. These findings bring new insights into the interactions of MTB with complex flow environments relevant to aquatic ecosystems, while suggesting opportunities for in vivo applications of MTB in microbiorobotics and targeted drug delivery.
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http://dx.doi.org/10.1002/smll.201702982 | DOI Listing |
Adv Mater
July 2025
Department of Biomedical Engineering, and Institute for Quantitative Health Science & Engineering, Michigan State University, East Lansing, MI, 48824, USA.
Nature's ability to create complex and functionalized organisms has long inspired engineers and scientists to develop increasingly advanced machines. Magnetotactic bacteria (MTB), a group of Gram-negative prokaryotes that biomineralize iron and thrive in aquatic environments, have garnered significant attention from the bioengineering community. These bacteria possess chains of magnetic nanocrystals known as magnetosomes, which allow them to align with Earth's geomagnetic field and navigate through aquatic environments via magnetotaxis, enabling localization to areas rich in nutrients and optimal oxygen concentration.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Commissariat à l'Energie Atomique (CEA), CNRS, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Aix-Marseille Université, Saint-Paul-lez-Durance 13115, France.
Magnetotactic bacteria have evolved the remarkable capacity to biomineralize chains of magnetite [Fe(II)Fe(III)O] nanoparticles that align along the geomagnetic field and optimize their navigation in the environment. Mechanisms enabling magnetite formation require the complex action of numerous proteins for iron acquisition, sequestration in dedicated magnetosome organelles, and precipitation into magnetite. The MamP protein contains c-type cytochromes called magnetochrome domains that are found exclusively in magnetotactic bacteria.
View Article and Find Full Text PDFSci Rep
November 2024
Key Laboratory for Humid Subtropical Ecogeographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou, 350117, China.
Bioengineering (Basel)
September 2023
Department of Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
Magnetotactic bacteria have great potential for use in biomedical and environmental applications due to the ability to direct their navigation with a magnetic field. Applying and accurately controlling a magnetic field within a microscopic region during bacterial magnetotaxis studies at the single-cell level is challenging due to bulky microscope components and the inherent curvilinear field lines produced by commonly used bar magnets. In this paper, a system that integrates microfluidics and electromagnetic coils is presented for generating a linear magnetic field within a microenvironment compatible with microfluidics, enabling magnetotaxis analysis of groups or single microorganisms on-chip.
View Article and Find Full Text PDFNatl Sci Rev
January 2023
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China.