Magnetotaxis in Prokaryotes

Abstract

Abstract Magnetotaxis refers to the behaviour of some motile, aquatic, bacteria that orient and swim along magnetic field lines. These microorganisms, called magnetotactic bacteria (MTB), contain intracellular structures known as magnetosomes, which are nano‐sized, magnetic, iron‐mineral crystals, each enveloped by a biological (phospholipid bilayer) membrane. Magnetosomes are usually arranged in chains within the cell, providing it with a permanent magnetic dipole moment that facilitates location and retention in the cell's preferred habitat at or below the oxic–anoxic interface in the water column or sediment. Although all MTB are motile by means of flagella and have a cell wall structure characteristic of Gram‐negative bacteria, their diversity is reflected by the large number of different morphotypes found in environmental samples of water or sediment, and by phylogenetic analysis of both cultured and uncultured organisms. Key Concepts: Prokaryotes (bacteria), like eukaryotes, internally compartmentalise and contain organelles. The prokaryotic flagellum rotates clockwise and counter clockwise thereby propelling the cell during swimming. Magnetotaxis is bacterial motility directed by a magnetic field. Magnetotactic bacteria contain intracellular, nano‐scale, membrane‐enveloped, magnetic iron‐mineral crystals called magnetosomes. Magnetosomes impart a permanent magnetic dipole moment to cells of magnetotactic bacteria causing them to behave as miniature, motile, compass needles. Magnetotaxis works in conjunction with aerotaxis to increase energy transduction in magnetotactic bacteria. Genes for magnetosome formation are clustered in a region of the genomes of magnetotactic bacteria known as a magnetosome gene or genomic island. Magnetotactic bacteria are important in the cycling of a number of important elements including carbon, iron, nitrogen and sulfur.