Magnetite, magnetotactic bacteria

Assimilatory Fe metabolism Fe biomolecules (siderophores, ferritin) magnetite (magnetotactic bacteria). 

Magnetite magnetotactic bacteria, tuna, salmon, pigeons Calcite mammals, fish Gypsum j ellyfish Barite chart... 

Biogenic magnetite magnetotactic bacteria protoctists. mollusks. arthropods, fish, birds human brain, meteorite )... 

Frankel RB, Blakemore RP, Wolfe RS (1979) Magnetite in freshwater magnetotactic bacteria. Science 203 1355-1356... 

Mandemack KW, Bazylinski DA, Shanks III WC, Bullen TD (1999) Oxygen and iron isotope studies of magnetite produced by magnetotactic bacteria. Science 285 1892-189 Mann S, Sparks NHC, Couling SB, Larcombe MC, Franke RB (1989) Crystallochemical characterization of magnetite spinels prepared from aqueous solution. J Chem Soc Far Trans 85 3033-3044 Matthews A, Zhu XK, O Nions K (2001) Kinetic iron stable isotope fractionation between iron (-II) and (-III) complexes in solution. Earth Planet Sci Lett 192 81-92... 

Fig. 7.14 Normalized decrease of the magnetization for magnetites of different origin. Whole cells refer to magnetotactic bacteria, extracted to biogenic magnetite extracted form these. The number indicates the size of synthetic magnetite crystals in nm (modified from Moskovitz etal., 1993, with permission).

Deep sea sediments may contain magnetite which may be not only of detrital origin, but may also contain a contribution from former magnetotactic bacteria. Petersen et al. (1986) have identified single-domain, magnetite crystals in Eocene to Quaternary sediments from the South Atlantic, which are very similar to biomagnetite in recent marine bacteria (see Chap. 17). 

Fig. 17.5 Shapes and intracellular arrangement of magneto-somes in various magnetotactic bacteria cubooctahedral (a), bullet-shaped (b,c), prismatic (d-k) and rectangular (I) magnetites arranged mostly in one or multiple chains, (Bar = 0.1 pm). (Schuler, 1999 with permission).

Stolz, J.E. Chang, S.R. Kirschvink, J.L (1986) Magnetotactic bacteria and single-domain magnetite in hemipelagic sediments. Nature 321 849-851... 

Figure 8 TEM of the magnetotactic bacteria of the Pettaquamescatt estuary (a) coccoid from 3.6 m, (b) vibrio from 7.2 m, (c) large rods with double row of magnetite crystallites, (d) moribund bacteria on surface of the sediment, (e) particles from 1 m depth. Scale bars = 100 nm (source Stolz, 1992, p. 138).

Mandemach, etal. (1999) Oxygen isotope studies of magnetite produced by magnetotactic bacteria. Science 285, 1892-1896. 

Shewanella oneidensis (formerly S. putrefaciens) produced and deposited an unidentified iron mineral intracellularly (Glasauer et al., 2002). Intracellular deposits of magnetite were previously known only from magnetotactic bacteria and a few higher organisms (Bazylinski and Moskowitz, 1997). 

---