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Critical single domain grain sizes in chains of interacting greigite particles: Implications for magnetosome crystals

Critical single domain grain sizes in chains of interacting greigite particles: Implications for magnetosome crystals
Critical single domain grain sizes in chains of interacting greigite particles: Implications for magnetosome crystals
Magnetotactic bacteria contain chains of magnetically interacting crystals (magnetosomes), which aid navigation (magnetotaxis). To improve the efficiency of magnetotaxis, magnetosome crystals (which can consist of magnetite or greigite) should be magnetically stable single domain (SD) particles. Larger particles subdivide into nonuniform multidomain (MD) magnetic structures that produce weaker magnetic signals, while small SD particles become magnetically unstable due to thermal fluctuations and exhibit superparamagnetic (SP) behavior. In this study, we determined the stable SD range as a function of grain elongation and interparticle separation for chains of identical greigite grains using fundamental parameters recently determined for greigite. Interactions significantly increase the stable SD range. For example, for cube-shaped greigite grains the upper stable SD threshold size is increased from 107 nm for isolated grains to 204 nm for touching grains arranged in chains. The larger critical SD grain size for greigite means that, compared to magnetite magnetosomes, greigite magnetosomes can produce larger magnetic signals without the need for intergrain interactions.
1525-2027
5430-5441
Muxworthy, Adrian R.
7fa5c819-b5ca-4354-83df-f9481b16ed1e
Williams, Wyn
d8b0d6be-3729-4126-a3ec-628638b75292
Roberts, Andrew P.
4f062491-5408-4edb-8dd1-140c6a42e93f
Winklhofer, Michael
a471c9f2-06f1-4a68-a8bd-11ef9f24aeb8
Chang, Liao
83123f49-dd71-43a9-a0b1-d80777231b44
Pósfai, Mihály
60962389-cd37-4ea3-ba41-5bd7e6fb0542
Muxworthy, Adrian R.
7fa5c819-b5ca-4354-83df-f9481b16ed1e
Williams, Wyn
d8b0d6be-3729-4126-a3ec-628638b75292
Roberts, Andrew P.
4f062491-5408-4edb-8dd1-140c6a42e93f
Winklhofer, Michael
a471c9f2-06f1-4a68-a8bd-11ef9f24aeb8
Chang, Liao
83123f49-dd71-43a9-a0b1-d80777231b44
Pósfai, Mihály
60962389-cd37-4ea3-ba41-5bd7e6fb0542

Muxworthy, Adrian R., Williams, Wyn, Roberts, Andrew P., Winklhofer, Michael, Chang, Liao and Pósfai, Mihály (2013) Critical single domain grain sizes in chains of interacting greigite particles: Implications for magnetosome crystals. Geochemistry, Geophysics, Geosystems, 14 (12), 5430-5441. (doi:10.1002/2013GC004973).

Record type: Article

Abstract

Magnetotactic bacteria contain chains of magnetically interacting crystals (magnetosomes), which aid navigation (magnetotaxis). To improve the efficiency of magnetotaxis, magnetosome crystals (which can consist of magnetite or greigite) should be magnetically stable single domain (SD) particles. Larger particles subdivide into nonuniform multidomain (MD) magnetic structures that produce weaker magnetic signals, while small SD particles become magnetically unstable due to thermal fluctuations and exhibit superparamagnetic (SP) behavior. In this study, we determined the stable SD range as a function of grain elongation and interparticle separation for chains of identical greigite grains using fundamental parameters recently determined for greigite. Interactions significantly increase the stable SD range. For example, for cube-shaped greigite grains the upper stable SD threshold size is increased from 107 nm for isolated grains to 204 nm for touching grains arranged in chains. The larger critical SD grain size for greigite means that, compared to magnetite magnetosomes, greigite magnetosomes can produce larger magnetic signals without the need for intergrain interactions.

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More information

Published date: December 2013
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 362776
URI: http://eprints.soton.ac.uk/id/eprint/362776
ISSN: 1525-2027
PURE UUID: 8fc45e40-46ef-433f-be85-5d84c0e15876

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Date deposited: 06 Mar 2014 10:34
Last modified: 08 Jan 2022 06:11

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Contributors

Author: Adrian R. Muxworthy
Author: Wyn Williams
Author: Andrew P. Roberts
Author: Michael Winklhofer
Author: Liao Chang
Author: Mihály Pósfai

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