phototrophic and autochthonous and characterized by high productivity, which is
due to (1) unlimited source of substrate (inorganic carbon) for phototrophs, (2) high
sunlight incidence, and (3) the variety of substances circulating inside the community and deriving from the decay of the primary producers’ biomass after they die
off. Considering the duration of existence of phototrophic microbial communities on
Earth and provided similarity of geological features of formation of alkaline water
bodies, it will not be surprising to find similar communities on other planets [12]. To
assess the biodiversity of the soda lakes microbiomes and to find particular microorganisms out there, the reader is referred to the recently published excellent Grant
and Jones’ survey [9], and therefore alkaliphiles from soda lakes will not be
mentioned more in this chapter. It can only be noted that despite most of the
known taxa of alkaliphiles have been isolated from soda waterbodies, their potential
as a source of valuable microorganisms has not yet been exhausted, and ongoing
publications on the description of new alkaliphiles from soda lakes can easily be
found in the literature.
2.1 The Sites of Serpentinization
Another geochemical alkaline system is presented by the serpentinization process
which is a metamorphic transformation of olivine- and pyroxene-rich rocks by water
into minerals of the serpentine group. Serpentinization is a rather complex cascade of
reactions [13], and the first step is characterized by dissolution of silicates that is
accompanied by a concomitant increase in the ambient pH:
For forsterite the species of olivine
ð
Þ : Mg 2 SiO 4 þ 2H 2 O
¼ 2Mg
2þ
þ SiO 2 aq
ð Þ þ 4OH
À
For enstatite the species of pyroxene
ð
Þ : Mg 2 Si 2 O 6 þ 2H 2 O
¼ 2Mg
2þ
þ 2SiO 2 aq
ð Þ þ 4OH
À
The serpentinizing systems can be both terrestrial and submarine. Unlike soda
lakes, alkalinity is generated by hydroxyl anions, and for terrestrial systems where
the presence of carbonates is minimal, the pH can reach 12. The sites of
serpentinization are less abundant and more diverse in ionic composition comparatively to carbonate systems. The process of serpentinization as a geochemical
phenomenon has been known since the twentieth century [14], but only with the
onset of the era of molecular techniques, a large variety of microorganisms
inhabiting these extreme places has been discovered. Terrestrial sites of modern
serpentinization with outflowing alkaline waters are found in Jordan [15], Portugal
[16], Newfoundland, Canada [17], the Philippines [18], northern Italy [19], Oman
[20], Turkey [21], Costa Rica [22], and the Cedars springs in California [23]. How
this interesting geochemical system works can be seen on the example of the Cedars
springs (Fig. 1).
Isolation and Cultivation of Alkaliphiles
57
due to (1) unlimited source of substrate (inorganic carbon) for phototrophs, (2) high
sunlight incidence, and (3) the variety of substances circulating inside the community and deriving from the decay of the primary producers’ biomass after they die
off. Considering the duration of existence of phototrophic microbial communities on
Earth and provided similarity of geological features of formation of alkaline water
bodies, it will not be surprising to find similar communities on other planets [12]. To
assess the biodiversity of the soda lakes microbiomes and to find particular microorganisms out there, the reader is referred to the recently published excellent Grant
and Jones’ survey [9], and therefore alkaliphiles from soda lakes will not be
mentioned more in this chapter. It can only be noted that despite most of the
known taxa of alkaliphiles have been isolated from soda waterbodies, their potential
as a source of valuable microorganisms has not yet been exhausted, and ongoing
publications on the description of new alkaliphiles from soda lakes can easily be
found in the literature.
2.1 The Sites of Serpentinization
Another geochemical alkaline system is presented by the serpentinization process
which is a metamorphic transformation of olivine- and pyroxene-rich rocks by water
into minerals of the serpentine group. Serpentinization is a rather complex cascade of
reactions [13], and the first step is characterized by dissolution of silicates that is
accompanied by a concomitant increase in the ambient pH:
For forsterite the species of olivine
ð
Þ : Mg 2 SiO 4 þ 2H 2 O
¼ 2Mg
2þ
þ SiO 2 aq
ð Þ þ 4OH
À
For enstatite the species of pyroxene
ð
Þ : Mg 2 Si 2 O 6 þ 2H 2 O
¼ 2Mg
2þ
þ 2SiO 2 aq
ð Þ þ 4OH
À
The serpentinizing systems can be both terrestrial and submarine. Unlike soda
lakes, alkalinity is generated by hydroxyl anions, and for terrestrial systems where
the presence of carbonates is minimal, the pH can reach 12. The sites of
serpentinization are less abundant and more diverse in ionic composition comparatively to carbonate systems. The process of serpentinization as a geochemical
phenomenon has been known since the twentieth century [14], but only with the
onset of the era of molecular techniques, a large variety of microorganisms
inhabiting these extreme places has been discovered. Terrestrial sites of modern
serpentinization with outflowing alkaline waters are found in Jordan [15], Portugal
[16], Newfoundland, Canada [17], the Philippines [18], northern Italy [19], Oman
[20], Turkey [21], Costa Rica [22], and the Cedars springs in California [23]. How
this interesting geochemical system works can be seen on the example of the Cedars
springs (Fig. 1).
Isolation and Cultivation of Alkaliphiles
57