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Laser Raman Spectroscopic Study on Magnetite Formation in Magnetotactic Bacteria

2009; Japan Institute of Metals and Materials; Volume: 73; Issue: 5 Linguagem: Inglês

10.2320/jinstmet.73.334

1880-6880

Shingo Watanabe, Masaharu Yamanaka, Akira Sakai, Ken Sawada, Tatsuo Iwasa,

Geology and Paleoclimatology Research

Magnetotactic bacteria have one or more chains of magnetosome, consisting of nano-sized magnetic crystal covered with a phospholipid bilayer and use it to sense the geomagnetic fields. In order to elucidate the molecular process to make magnetosome from the iron compounds found in the bacteria, laser Raman spectroscopic measurements were performed with the magnetotactic bacterium, Magnetospirillum magnetotacticum MS-1 and the fractions separated from it. The clear Raman signals were observed at 662 cm-1 and 740 cm-1. The former was observed in whole cell and magnetosome fraction, but not in membrane and cytoplasmic fraction and assigned to the Raman signal of magnetite. The Raman signal of the latter was observed not only in the magnetosome fraction, but also in the cytoplasmic fraction and membrane fraction. This signal was assumed to ferrihydrite. Based on the results, the pathway of the magnetosome synthesis and possible roles of ferrihydrite in the magnetotactic bacteria were discussed.