from the vents with the seawater, a strong precipitation of minerals occurs above the
vent; black, cloud-like sulfide minerals are precipitated as microscopic particles in
the venting water, giving those vents the name “black smokers.” While those black
smokers are in direct contact with the magma chambers that are found 1–3 km
beneath the seafloor, a second group of hydrothermal vents exists, the Lost City
hydrothermal systems (Martin et al. 2008). This circulation system (~200
C) has no
intimate connection with the magma chambers, and lacks CO 2 but provides high
fluxes of hydrogen and methane at high pH.
The mineralization steps at the black smokers involving chalcopyrite, pyrrhotite,
anhydrite, pyrite, and sphalerite are driven by the temperature decrease and can be
explained on the basis of chemical reaction processes only, not involving any
biogenic component (Halbach et al. 2003; Herzig and Hannington 2006);
Fig. 4.18. Likewise, even though vents provide rich substrates for bacterial
communities, e.g., chemosynthetic bacteria or a wide array of Metazoa (Suess
et al. 1998), no data exist about a potential involvement of microorganisms in
vent formation. In contrast, it is more likely that those black smoker-associated
microorganisms modify or convert those pyrite derivatives to their oxidation
products. One well-studied pyrite-oxidizing bacterium is the gram-negative
Ferrobacillus ferrooxidans/Acidithiobacillus ferrooxidans that obtains energy
from the oxidation of ferrous iron or reduced sulfur compounds (Silverman
1967). From this bacterium, it is also known that it produces a biofilm (Mangold
et al. 2008). Hence, it can be proposed that A. ferrooxidans-related microorganisms
(Spiridonova et al. 2006) might exist on the surface of the pyrite crystals and
convert them to an accessible area for a wide range of microorganism. First data
on such pyrite modifications, from pyrite crystals to amorphous-looking mats
composed of Fe and S, had been obtained from black smoker rocks, collected by
“Ocean 1” (Lin and Zhang 2006).
4.7 Toward a Molecular Biomineralization
The biomineralization concept provides new avenues for a sustainable exploitation
of economically important biominerals, e.g., nodules and vents, since it implements
molecular biology as a powerful technique to the understanding of mineralization
processes. Application of recent electron microscopic and spectroscopic techniques
disclosed the participation of organic molecules in the mineralization processes.
Prominent examples are the formation of bio-silica in diatoms or sponges (M€ uller
2003). In the latter model, even enzymatic activities could be implicated in the
mineral deposition. This insight allowed the application of the recombinant technology for the production of inorganic polymers at lower temperature and mild
reaction conditions (M€ uller et al. 2007b; Schr€ oder et al. 2008). Following this
strategy, intense efforts yielded the elucidation that defined organisms, bacteria in
nodules and coccoliths, in crusts are involved in the deposition of marine minerals,
104
X. Wang et al.
vent; black, cloud-like sulfide minerals are precipitated as microscopic particles in
the venting water, giving those vents the name “black smokers.” While those black
smokers are in direct contact with the magma chambers that are found 1–3 km
beneath the seafloor, a second group of hydrothermal vents exists, the Lost City
hydrothermal systems (Martin et al. 2008). This circulation system (~200
C) has no
intimate connection with the magma chambers, and lacks CO 2 but provides high
fluxes of hydrogen and methane at high pH.
The mineralization steps at the black smokers involving chalcopyrite, pyrrhotite,
anhydrite, pyrite, and sphalerite are driven by the temperature decrease and can be
explained on the basis of chemical reaction processes only, not involving any
biogenic component (Halbach et al. 2003; Herzig and Hannington 2006);
Fig. 4.18. Likewise, even though vents provide rich substrates for bacterial
communities, e.g., chemosynthetic bacteria or a wide array of Metazoa (Suess
et al. 1998), no data exist about a potential involvement of microorganisms in
vent formation. In contrast, it is more likely that those black smoker-associated
microorganisms modify or convert those pyrite derivatives to their oxidation
products. One well-studied pyrite-oxidizing bacterium is the gram-negative
Ferrobacillus ferrooxidans/Acidithiobacillus ferrooxidans that obtains energy
from the oxidation of ferrous iron or reduced sulfur compounds (Silverman
1967). From this bacterium, it is also known that it produces a biofilm (Mangold
et al. 2008). Hence, it can be proposed that A. ferrooxidans-related microorganisms
(Spiridonova et al. 2006) might exist on the surface of the pyrite crystals and
convert them to an accessible area for a wide range of microorganism. First data
on such pyrite modifications, from pyrite crystals to amorphous-looking mats
composed of Fe and S, had been obtained from black smoker rocks, collected by
“Ocean 1” (Lin and Zhang 2006).
4.7 Toward a Molecular Biomineralization
The biomineralization concept provides new avenues for a sustainable exploitation
of economically important biominerals, e.g., nodules and vents, since it implements
molecular biology as a powerful technique to the understanding of mineralization
processes. Application of recent electron microscopic and spectroscopic techniques
disclosed the participation of organic molecules in the mineralization processes.
Prominent examples are the formation of bio-silica in diatoms or sponges (M€ uller
2003). In the latter model, even enzymatic activities could be implicated in the
mineral deposition. This insight allowed the application of the recombinant technology for the production of inorganic polymers at lower temperature and mild
reaction conditions (M€ uller et al. 2007b; Schr€ oder et al. 2008). Following this
strategy, intense efforts yielded the elucidation that defined organisms, bacteria in
nodules and coccoliths, in crusts are involved in the deposition of marine minerals,
104
X. Wang et al.