by microbial cell surface which serves as nucleation and crystal growth sites. This
process happens due to the nature of cell surfaces. Bacterial cell walls and external
sheaths are rich in chemically reactive negatively charged sites that readily bind to
dissolved mineral-forming elements. The adsorption substantially minimizes the
activation energy barrier which normally inhibits the spontaneous nucleation and
crystal growth. The mineral crystallization on the surface of the cells leads to
complete encrustation. Part of the iron oxides, phosphates, carbonates, and clays
precipitation happens in this way. The hot spring bacteria-induced amorphous silica
precipitation is a good example of the passive type of microbial biomineralization.
On the other hand, the active biomineralization (BCM) process is a complex process
arbitrated by the metabolic activity of organisms. The nucleation as well as the
growth of the mineral particles are often controlled by intricate metabolic activities.
In this scenario, the organisms produce minerals that are unique to the species, and it
happens without the influence of the environment. This biomineralization process
can happen in two distinct ways, directly through enzymatic modification of minerals or by triggering change in the vicinity of minerals that leads to precipitation.
The enzyme-mediated reductive uraninite precipitation by some metal-reducing
bacteria [42], the accumulation of tiny magnetite particles by magnetotactic bacteria
[36], and silica deposition by coccolithophores and diatoms [28, 43] are examples of
this type of biomineralization process. Bacteria-mediated gold and silver accumulation is also a reductive precipitation of an active biomineralization process [44, 45].
In some cases, the active biomineralization process is related to complex metabolic activities that can change the solution chemistry which tends to promote
mineral oversaturation and its subsequent precipitation. One example is the metabolic activity of photosynthetic cyanobacteria that increases the pH of the aquatic
environment in which they are living [46]. The rise in pH of the water leads to
precipitation of carbonate minerals like calcite (CaCO 3 ) and strontianite (SrCO 3 )
[47]. In a similar way, the metabolic activities of microorganisms induce production
of mackinawite, pyrite, and other sulfide minerals [48].
Microbial-based carbonate precipitation plays a vital role in metal coprecipitation
which has cementation function in natural systems including soil, caves, and aquatic
bodies [6]. This process, which occurs in different geological sceneries, can be
mimicked and implemented in different biotechnological applications including
metal remediation, enhanced oil recovery, carbon sequestration, and construction
restoration [49–52]. The major focus of this chapter is on calcite precipitation by this
intriguing natural process and its role in enhancing the durability of concrete
structures. In addition to calcite, silica precipitation has also potential in concrete
application. Thus, microbially induced calcite and silicate precipitation are discussed
below.
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process happens due to the nature of cell surfaces. Bacterial cell walls and external
sheaths are rich in chemically reactive negatively charged sites that readily bind to
dissolved mineral-forming elements. The adsorption substantially minimizes the
activation energy barrier which normally inhibits the spontaneous nucleation and
crystal growth. The mineral crystallization on the surface of the cells leads to
complete encrustation. Part of the iron oxides, phosphates, carbonates, and clays
precipitation happens in this way. The hot spring bacteria-induced amorphous silica
precipitation is a good example of the passive type of microbial biomineralization.
On the other hand, the active biomineralization (BCM) process is a complex process
arbitrated by the metabolic activity of organisms. The nucleation as well as the
growth of the mineral particles are often controlled by intricate metabolic activities.
In this scenario, the organisms produce minerals that are unique to the species, and it
happens without the influence of the environment. This biomineralization process
can happen in two distinct ways, directly through enzymatic modification of minerals or by triggering change in the vicinity of minerals that leads to precipitation.
The enzyme-mediated reductive uraninite precipitation by some metal-reducing
bacteria [42], the accumulation of tiny magnetite particles by magnetotactic bacteria
[36], and silica deposition by coccolithophores and diatoms [28, 43] are examples of
this type of biomineralization process. Bacteria-mediated gold and silver accumulation is also a reductive precipitation of an active biomineralization process [44, 45].
In some cases, the active biomineralization process is related to complex metabolic activities that can change the solution chemistry which tends to promote
mineral oversaturation and its subsequent precipitation. One example is the metabolic activity of photosynthetic cyanobacteria that increases the pH of the aquatic
environment in which they are living [46]. The rise in pH of the water leads to
precipitation of carbonate minerals like calcite (CaCO 3 ) and strontianite (SrCO 3 )
[47]. In a similar way, the metabolic activities of microorganisms induce production
of mackinawite, pyrite, and other sulfide minerals [48].
Microbial-based carbonate precipitation plays a vital role in metal coprecipitation
which has cementation function in natural systems including soil, caves, and aquatic
bodies [6]. This process, which occurs in different geological sceneries, can be
mimicked and implemented in different biotechnological applications including
metal remediation, enhanced oil recovery, carbon sequestration, and construction
restoration [49–52]. The major focus of this chapter is on calcite precipitation by this
intriguing natural process and its role in enhancing the durability of concrete
structures. In addition to calcite, silica precipitation has also potential in concrete
application. Thus, microbially induced calcite and silicate precipitation are discussed
below.
300
G. Mamo and B. Mattiasson