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
- 196 Downloads
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.
KeywordsMulticellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis North seeking South seeking Swimming polarity Magnetotaxis
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.
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)
- Esquivel DMS, Lins de Barros HGP (1986) Motion of magnetotactic microorganisms. J Exp Biol 121:153–163Google Scholar
- Keim CN, Martins JL, Lins de Barros H, Lins U, Farina M (2006) Structure, behavior, ecology and diversity of multicelular magnetotactic prokaryotes. In: Schuler D (ed) Magnetoreception and magnetosomes in bacteria. Springer-Verlag, Berlin, pp 103–132Google Scholar