Chemotaxis in external fields: Simulations for active magnetic biological matter.

The movement of microswimmers is often described by active Brownian particle models. Here we introduce a variant of these models with several internal states of the swimmer to describe stochastic strategies for directional swimming such as run and tumble or run and reverse that are used by microorga...

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Main Authors: Agnese Codutti, Klaas Bente, Damien Faivre, Stefan Klumpp
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2019-12-01
Series:PLoS Computational Biology
Online Access:https://journals.plos.org/ploscompbiol/article/file?id=10.1371/journal.pcbi.1007548&type=printable
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author Agnese Codutti
Klaas Bente
Damien Faivre
Stefan Klumpp
author_facet Agnese Codutti
Klaas Bente
Damien Faivre
Stefan Klumpp
author_sort Agnese Codutti
collection DOAJ
description The movement of microswimmers is often described by active Brownian particle models. Here we introduce a variant of these models with several internal states of the swimmer to describe stochastic strategies for directional swimming such as run and tumble or run and reverse that are used by microorganisms for chemotaxis. The model includes a mechanism to generate a directional bias for chemotaxis and interactions with external fields (e.g., gravity, magnetic field, fluid flow) that impose forces or torques on the swimmer. We show how this modified model can be applied to various scenarios: First, the run and tumble motion of E. coli is used to establish a paradigm for chemotaxis and investigate how it is affected by external forces. Then, we study magneto-aerotaxis in magnetotactic bacteria, which is biased not only by an oxygen gradient towards a preferred concentration, but also by magnetic fields, which exert a torque on an intracellular chain of magnets. We study the competition of magnetic alignment with active reorientation and show that the magnetic orientation can improve chemotaxis and thereby provide an advantage to the bacteria, even at rather large inclination angles of the magnetic field relative to the oxygen gradient, a case reminiscent of what is expected for the bacteria at or close to the equator. The highest gain in chemotactic velocity is obtained for run and tumble with a magnetic field parallel to the gradient, but in general a mechanism for reverse motion is necessary to swim against the magnetic field and a run and reverse strategy is more advantageous in the presence of a magnetic torque. This finding is consistent with observations that the dominant mode of directional changes in magnetotactic bacteria is reversal rather than tumbles. Moreover, it provides guidance for the design of future magnetic biohybrid swimmers.
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spelling doaj-art-74486c2597314c16a4ecbae99f2197d82025-08-20T02:17:05ZengPublic Library of Science (PLoS)PLoS Computational Biology1553-734X1553-73582019-12-011512e100754810.1371/journal.pcbi.1007548Chemotaxis in external fields: Simulations for active magnetic biological matter.Agnese CoduttiKlaas BenteDamien FaivreStefan KlumppThe movement of microswimmers is often described by active Brownian particle models. Here we introduce a variant of these models with several internal states of the swimmer to describe stochastic strategies for directional swimming such as run and tumble or run and reverse that are used by microorganisms for chemotaxis. The model includes a mechanism to generate a directional bias for chemotaxis and interactions with external fields (e.g., gravity, magnetic field, fluid flow) that impose forces or torques on the swimmer. We show how this modified model can be applied to various scenarios: First, the run and tumble motion of E. coli is used to establish a paradigm for chemotaxis and investigate how it is affected by external forces. Then, we study magneto-aerotaxis in magnetotactic bacteria, which is biased not only by an oxygen gradient towards a preferred concentration, but also by magnetic fields, which exert a torque on an intracellular chain of magnets. We study the competition of magnetic alignment with active reorientation and show that the magnetic orientation can improve chemotaxis and thereby provide an advantage to the bacteria, even at rather large inclination angles of the magnetic field relative to the oxygen gradient, a case reminiscent of what is expected for the bacteria at or close to the equator. The highest gain in chemotactic velocity is obtained for run and tumble with a magnetic field parallel to the gradient, but in general a mechanism for reverse motion is necessary to swim against the magnetic field and a run and reverse strategy is more advantageous in the presence of a magnetic torque. This finding is consistent with observations that the dominant mode of directional changes in magnetotactic bacteria is reversal rather than tumbles. Moreover, it provides guidance for the design of future magnetic biohybrid swimmers.https://journals.plos.org/ploscompbiol/article/file?id=10.1371/journal.pcbi.1007548&type=printable
spellingShingle Agnese Codutti
Klaas Bente
Damien Faivre
Stefan Klumpp
Chemotaxis in external fields: Simulations for active magnetic biological matter.
PLoS Computational Biology
title Chemotaxis in external fields: Simulations for active magnetic biological matter.
title_full Chemotaxis in external fields: Simulations for active magnetic biological matter.
title_fullStr Chemotaxis in external fields: Simulations for active magnetic biological matter.
title_full_unstemmed Chemotaxis in external fields: Simulations for active magnetic biological matter.
title_short Chemotaxis in external fields: Simulations for active magnetic biological matter.
title_sort chemotaxis in external fields simulations for active magnetic biological matter
url https://journals.plos.org/ploscompbiol/article/file?id=10.1371/journal.pcbi.1007548&type=printable
work_keys_str_mv AT agnesecodutti chemotaxisinexternalfieldssimulationsforactivemagneticbiologicalmatter
AT klaasbente chemotaxisinexternalfieldssimulationsforactivemagneticbiologicalmatter
AT damienfaivre chemotaxisinexternalfieldssimulationsforactivemagneticbiologicalmatter
AT stefanklumpp chemotaxisinexternalfieldssimulationsforactivemagneticbiologicalmatter