Magnetotactic bacteria were discovered almost 30 years ago, and for many years and many different reasons, the number of researchers working in this field was few and progress was slow. Recently, however, thanks to the isolation of new strains and the development of new techniques for manipulating these strains, researchers from several laboratories have made significant progress in elucidating the molecular, biochemical, chemical and genetic bases of magnetosome formation and understanding how these unique intracellular organelles function. We focus here on this progress.

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Magnetosome formation in prokaryotes

Magnetotactic Bacteria and Magnetosomes

Dissolution and pyritization of magnetite in anoxie marine sediments

The most likely occasion that soil scientists will come in contact with Fe oxides is when they note and try to explain the colors of soils. Many of these soil colors, notably those between red, brown, and yellow, are due to solid Fe oxides. Green-blue colors may also be explained by Fe compounds and even gray colors, although in a negative sense, reflect certain parts of the Fe cycle because the gray colors may indicate the removal of Fe oxides by microbial reduction.

Occurrence and Formation of Iron Oxides in Various Pedoenvironments

Intact magnetosomes of Aquaspirillum magnetotacticum were purified from broken cells by a magnetic separation technique. Electron microscopic and chemical analyses revealed the magnetite to be enclosed by a lipid bilayer admixed with proteins. Lipids were recovered in fractions expected to contain (i) neutral lipids and free fatty acids, (ii) glycolipids and sulfolipids, and (iii) phospholipids (in a weight ratio of 1:4:6). Phospholipids included phosphatidylserine and phosphatidylethanolamine. Two of the numerous proteins detected in the magnetosome membrane were not found in other cell membranes or soluble fractions.

T.T. Moench

Papers

Electron-optical characterization of bacterial magnetite