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European Biophysics Journal

, Volume 46, Issue 6, pp 533–539 | Cite as

The swimming polarity of multicellular magnetotactic prokaryotes can change during an isolation process employing magnets: evidence of a relation between swimming polarity and magnetic moment intensity

  • Roger Duarte de Melo
  • Daniel Acosta-AvalosEmail author
Original Article

Abstract

Magnetotactic microorganisms are characterized by swimming in the direction of an applied magnetic field. In nature, two types of swimming polarity have been observed: north-seeking microorganisms that swim in the same direction as the magnetic field, and south-seeking microorganisms that swim in the opposite direction. The present work studies the reversal in the swimming polarity of the multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis following an isolation process using high magnetic fields from magnets. The proportion of north- and south-seeking organisms was counted as a function of the magnetic field intensity used during the isolation of the organisms from sediment. It was observed that the proportion of north-seeking organisms increased when the magnetic field was increased. The magnetic moment for north- and south-seeking populations was estimated using the U-turn method. The average magnetic moment was higher for north- than south-seeking organisms. The results suggest that the reversal of swimming polarity must occur during the isolation process in the presence of high magnetic fields and magnetic field gradients. It is shown for the first time that the swimming polarity reversal depends on the magnetic moment intensity of multicellular magnetotactic prokaryotes, and new studies must be undertaken to understand the role of magnetic moment polarity and oxygen gradients in determination of swimming polarity.

Keywords

Multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis North seeking South seeking Swimming polarity Magnetotaxis 

Notes

Acknowledgements

The authors thank Dr. Henrique Lins de Barros for fruitful discussion and suggestions, Dr. Steven Frederick Durrant from UNESP, Sorocaba, SP, Brazil for correcting the English of the manuscript, and the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico—CNPq, Brazil and Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro—FAPERJ, Rio de Janeiro, Brazil for financial support.

Supplementary material

249_2017_1199_MOESM1_ESM.pdf (130 kb)
Table II: Values for the radius R, U-turn time t u, ratio t u/R 3, and corresponding values for the magnetic moment m, calculated using Eq. (1), ordered according to the magnetic field used in the isolation process and the type of swimming polarity. The corresponding statistics are summarized in Table I (PDF 130 kb)

Video 1: Isolation of MMPs with the magnetic south pole facing the capillary end. The magnetic field measured at the capillary end was 460 Oe. The video starts at the drop border where SS MMPs should accumulate (3gp 3330 kb)

Video 2: Isolation of MMPs with the magnetic north pole facing the capillary end. The magnetic field measured at the capillary end was 460 Oe. The video starts at the drop border where SS MMPs should accumulate (3gp 4650 kb)

Video 3: Isolation of MMPs with the magnetic north pole facing the capillary end. The magnetic field measured at the capillary end was 15 Oe. The video starts at the drop border where SS MMPs should accumulate (3gp 3789 kb)

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Copyright information

© European Biophysical Societies' Association 2017

Authors and Affiliations

  1. 1.Centro Brasileiro de Pesquisas FisicasRio de JaneiroBrazil

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