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媽的...就是有這種沒品的人...機車
: : 請問magnetotactic bacteria攜帶重金屬的機制是什麼?有人可以告訴我嗎?
: : 謝謝喔!
: 1)如果是班上同學，下面這一篇加減看，然後提到的文獻也可以看看吧
: http://www.agu.org/revgeophys/moskow01/node2.html
: 2)如果是路人.....你是不會自己去查喔...google你是不會用喔...圖書館是不會用喔
: Magnetotactic Bacteria
: Magnetotactic bacteria (MTB) orient and migrate along the geomagnetic field
: towards favorable habitats, a behavior known as magnetotaxis. Since the first
: report of magnetotactic bacteria by Blakemore [1975], subsequent studies have
: shown that MTB are a morphologically diverse and cosmopolitan group of
: aquatic microorganisms inhabiting freshwater and marine environments ranging
: from aerobic to anoxic. Three significant findings since the last IUGG report
: on biomineralization are (1) an increase in the types of environments where
: MTB are found besides microaerobic to include anaerobic and aerobic
: [ Bazylinski, 1990; Matsunaga et al., 1991; Sakaguchi et al., 1993]; (2) an
: increase in the number of identified phases besides magnetite (FeO) to
: include ferrimagnetic greigite (FeS), possible pyrrhotite (FeS), and
: non-magnetic pyrite (FeS) [ Mann et al., 1990a; Farina et al., 1990;
: Bazylinski, 1990]; and (3) the discovery of non-magnetotactic magnetite
: producing bacteria [ Lovley, 1990].
: In natural habitats, large populations of MTB are usually found near the
: oxic-anoxic transition zone, which is usually located at the sediment-water
: interface in freshwater environments or displaced upward into the water column
: in marine semi-anaerobic environments [ Stolz, 1992; Bazylinski and Frankel,
: 1992]. In the latter types of environments, magnetite and greigite producing
: MTB exist in horizontal zones at specific water depths depending on the
: vertical chemical and redox gradients [ Stolz, 1992; Bazylinski, 1991].
: Petermann and Bleil [1993] identify several different types of living MTB in
: deep sea sediments from the South Atlantic, some at water depths of 2000 m.
: Magnetic bacteria containing intercellular magnetite particles have also been
: identified in the uppermost horizon of a waterlogged soil in Germany
: [ Fassbinder et al., 1990]. Although population densities of the magnetic
: bacteria were too low at the time of sampling to contribute significantly to
: the magnetism of the soil, the authors suggest that population densities can
: change dramatically depending on microenvironmental conditions. However, the
: question of a biogenic magnetic component in soil must await further
: confirmation and study.
: Magnetotactic bacteria from reducing environments with high concentrations of
: HS contain Fe-sulphide particles instead of Fe-oxides [ Mann et al., 1990a;
: Farina et al., 1990; Bazylinski and Frankel, 1992]. The sulphide minerals were
: identified by indexing single crystal electron diffraction patterns [ Mann et
: al., 1990a; Heywood et al., 1990, 1991]. Several types of bacteria have been
: studied including a rod shaped bacterium containing only greigite particles
: [ Bazylinski, 1990], a multicellular magnetotactic prokaryote (MMP) containing
: a mixture of greigite and pyrite particles [ Mann et al., 1990a], and another
: bacterium containing both magnetite and greigite particles [ Bazylinski et al.,
: 1993a]. In another study, ferrimagnetic pyrrhotite (FeS) was proposed as the
: iron-sulfide mineral in a similar (or perhaps the same) MMP from Brazil [
: Farina et al., 1990]. No single crystal diffraction patterns have yet been
: obtained that unequivocally identify the phase as pyrrhotite, so the report
: of FeS in MTB remains problematical. Finally, Sakaguchi et al. [1993] report
: a magnetotactic sulphate-reducing bacterium that produces intercellular
: magnetite and extracellular magnetic iron-sulfide particles. This discovery
: extends the range of magnetite producing microorganisms to sedimentary levels
: where sulphate reduction occurs.
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