3.4.4.3 Uptake of Other Inorganic Compounds,
Trace Elements, and Essential Factors
Under the action of ATP synthase, phosphate that enters the
cell by specific carrier reacts with ADP to give ATP. ATP is
the source of phosphate for the synthesis of macromolecules,
in particular nucleic acids, phospholipids, and nucleotides.
Microorganisms should find other mineral compounds in
their environment such as the general anions and cations
which penetrate cells by carrier systems. Potassium, calcium, magnesium, and iron are major elements essential to
the cells for several reasons, including enzyme cofactors.
Magnesium is present in cell walls, membranes, and phosphoric esters, calcium in coenzymes and bacterial spores in
the form of dipicolinate, and iron in metalloproteins
(cytochromes, ferredoxins, and iron–sulfur proteins). In
oxic environments, extremely insoluble ferric salts are inaccessible to microorganisms. For that reason, microorganisms
produce and excrete organic compounds or siderophores that
chelate and trap iron (cf. Sect. 14.5.2). This chelated iron is
absorbed by the cells. However, in anoxic environments,
iron present in the form of soluble ferrous iron is readily
available to cells.
In general the sodium requirements are low, except in
halophilic
microorganisms
that
require
higher
concentrations of ions Na
+ in their environment and sometimes accumulate in the cytoplasm to compensate osmotic
pressure. Diatoms are important needs in silicon, an element
essential to the formation of cell walls.
In addition to these compounds, many other elements
or trace elements are needed in low concentrations for
cellular activities. These are mainly manganese, zinc,
molybdenum, selenium, cobalt, nickel, copper, and tungsten. They act as enzyme cofactors or integral part of
enzymes.
3.5
Conclusion
Unlike their poorly differentiated structures compared to
eukaryotes, prokaryotes have a very diverse metabolism
especially in their energy sources (organic or inorganic
substrates used through different aerobic and anaerobic
respirations, fermentations, or photosynthesis) placing
them as key actors with the major role in the transformation
of organic or inorganic elements on the planet (cf. Chap. 14).
Moreover, the metabolic versatility of many prokaryotes
gives them a plasticity allowing their adaptation to changing
environmental conditions. For example, members of the
genus Shewanella, facultative anaerobic bacteria that grow
in chemolithotrophic conditions with dihydrogen as an
energy source or in chemoorganotrophic conditions, exhibit
a very large diversity of respiration. In the absence of
dioxygen, many of organic or inorganic compounds,
including toxic elements and metals, are terminal electron
acceptors (trimethylamine oxide, iron III, manganese IV,
chromium VI, VI uranium, sulfur, polysulfide, sulfite, thiosulfate, dimethyl sulfoxide, arsenate, succinate, etc.). Similarly, some anoxygenic phototrophic bacteria show great
adaptability to environmental conditions. This is the case
of representatives of the genus Thiocapsa that, under anoxic
conditions and in the light, use light radiations as energy
source, reduced inorganic compounds of sulfur, dihydrogen,
and small organic molecules as electron source, and organic
molecules or carbon dioxide for their carbon source. Placed
in the dark, under oxic conditions, these microorganisms
exhibit an aerobic respiratory mechanism using organic
compounds or inorganic sulfur, and under anoxic conditions,
they ferment their intracellular reserves of polysaccharides
using intracellular sulfur as electron trap. Our knowledge on
the adaptability of microorganisms to environmental
conditions has increased with the discovery of unexpected
metabolic pathways such as aerobic respiration in bacteria
long time considered as strictly anaerobic (sulfate-reducing
bacteria) and anoxygenic photosynthesis in aerobic
chemoorganotrophic heterotrophic bacteria (aerobic
anoxygenic phototrophic bacteria).
Prokaryotes are the microorganisms most important in the
biodegradation processes, and thus they are used either
naturally or artificially in the processes of decontamination
and biopurification of anthropized ecosystems (cf. Chap. 16).
Eukaryotes have developed structures more and more complex with the recovery of both the most energetic prokaryotic
metabolisms, both in relation to dioxygen: aerobic respiration
and oxygenic photosynthesis.
References
Berg IA, Kockelkorn D, Ramos-Vera WH, Say RF, Zarzycki J, Hu ¨gler
M, Alber BE, Fuchs G (2010) Autotrophic carbon fixation in
Archaea. Nature rev 8:447–460
Carballido-Lo ´pez R (2006) The bacterial actin-like cytoskeleton.
Microbiol Mol Biol Rev 70:888–909
Danson MJ, Lamble HJ, Hough DW (2007) Central metabolism. In:
Cavicchioli R (ed) Archaea: molecular and cellular biology. ASM
Press, Washington, DC, pp 260–287
Deppenmeier U, Lienard T, Gottschalk G (1999) Novel reactions
involved in energy conservation by methanogenic archaea. FEBS
Letters 457:291–297
Detkova EN, Pusheva MA (2006) Energy metabolism in halophilic and
alkaliphilic acetogenic bacteria. Microbiology 75:1–11
Dubey GP, Ben-Yehuda S (2011) Intracellular nanotubes mediate
bacterial communication. Cell 144:590–600
Ettwig FK et al (2010) Nitrite-driven anaerobic methane oxidation by
oxygenic bacteria. Nature 464:543–547
Fuchs BM et al (2007) Characterization of a marine gammaproteobacterium capable of aerobic anoxygenic photosynthesis. Proc Natl
Acad Sci USA 104:2891–2896
70
R. Matheron and P. Caumette
Trace Elements, and Essential Factors
Under the action of ATP synthase, phosphate that enters the
cell by specific carrier reacts with ADP to give ATP. ATP is
the source of phosphate for the synthesis of macromolecules,
in particular nucleic acids, phospholipids, and nucleotides.
Microorganisms should find other mineral compounds in
their environment such as the general anions and cations
which penetrate cells by carrier systems. Potassium, calcium, magnesium, and iron are major elements essential to
the cells for several reasons, including enzyme cofactors.
Magnesium is present in cell walls, membranes, and phosphoric esters, calcium in coenzymes and bacterial spores in
the form of dipicolinate, and iron in metalloproteins
(cytochromes, ferredoxins, and iron–sulfur proteins). In
oxic environments, extremely insoluble ferric salts are inaccessible to microorganisms. For that reason, microorganisms
produce and excrete organic compounds or siderophores that
chelate and trap iron (cf. Sect. 14.5.2). This chelated iron is
absorbed by the cells. However, in anoxic environments,
iron present in the form of soluble ferrous iron is readily
available to cells.
In general the sodium requirements are low, except in
halophilic
microorganisms
that
require
higher
concentrations of ions Na
+ in their environment and sometimes accumulate in the cytoplasm to compensate osmotic
pressure. Diatoms are important needs in silicon, an element
essential to the formation of cell walls.
In addition to these compounds, many other elements
or trace elements are needed in low concentrations for
cellular activities. These are mainly manganese, zinc,
molybdenum, selenium, cobalt, nickel, copper, and tungsten. They act as enzyme cofactors or integral part of
enzymes.
3.5
Conclusion
Unlike their poorly differentiated structures compared to
eukaryotes, prokaryotes have a very diverse metabolism
especially in their energy sources (organic or inorganic
substrates used through different aerobic and anaerobic
respirations, fermentations, or photosynthesis) placing
them as key actors with the major role in the transformation
of organic or inorganic elements on the planet (cf. Chap. 14).
Moreover, the metabolic versatility of many prokaryotes
gives them a plasticity allowing their adaptation to changing
environmental conditions. For example, members of the
genus Shewanella, facultative anaerobic bacteria that grow
in chemolithotrophic conditions with dihydrogen as an
energy source or in chemoorganotrophic conditions, exhibit
a very large diversity of respiration. In the absence of
dioxygen, many of organic or inorganic compounds,
including toxic elements and metals, are terminal electron
acceptors (trimethylamine oxide, iron III, manganese IV,
chromium VI, VI uranium, sulfur, polysulfide, sulfite, thiosulfate, dimethyl sulfoxide, arsenate, succinate, etc.). Similarly, some anoxygenic phototrophic bacteria show great
adaptability to environmental conditions. This is the case
of representatives of the genus Thiocapsa that, under anoxic
conditions and in the light, use light radiations as energy
source, reduced inorganic compounds of sulfur, dihydrogen,
and small organic molecules as electron source, and organic
molecules or carbon dioxide for their carbon source. Placed
in the dark, under oxic conditions, these microorganisms
exhibit an aerobic respiratory mechanism using organic
compounds or inorganic sulfur, and under anoxic conditions,
they ferment their intracellular reserves of polysaccharides
using intracellular sulfur as electron trap. Our knowledge on
the adaptability of microorganisms to environmental
conditions has increased with the discovery of unexpected
metabolic pathways such as aerobic respiration in bacteria
long time considered as strictly anaerobic (sulfate-reducing
bacteria) and anoxygenic photosynthesis in aerobic
chemoorganotrophic heterotrophic bacteria (aerobic
anoxygenic phototrophic bacteria).
Prokaryotes are the microorganisms most important in the
biodegradation processes, and thus they are used either
naturally or artificially in the processes of decontamination
and biopurification of anthropized ecosystems (cf. Chap. 16).
Eukaryotes have developed structures more and more complex with the recovery of both the most energetic prokaryotic
metabolisms, both in relation to dioxygen: aerobic respiration
and oxygenic photosynthesis.
References
Berg IA, Kockelkorn D, Ramos-Vera WH, Say RF, Zarzycki J, Hu ¨gler
M, Alber BE, Fuchs G (2010) Autotrophic carbon fixation in
Archaea. Nature rev 8:447–460
Carballido-Lo ´pez R (2006) The bacterial actin-like cytoskeleton.
Microbiol Mol Biol Rev 70:888–909
Danson MJ, Lamble HJ, Hough DW (2007) Central metabolism. In:
Cavicchioli R (ed) Archaea: molecular and cellular biology. ASM
Press, Washington, DC, pp 260–287
Deppenmeier U, Lienard T, Gottschalk G (1999) Novel reactions
involved in energy conservation by methanogenic archaea. FEBS
Letters 457:291–297
Detkova EN, Pusheva MA (2006) Energy metabolism in halophilic and
alkaliphilic acetogenic bacteria. Microbiology 75:1–11
Dubey GP, Ben-Yehuda S (2011) Intracellular nanotubes mediate
bacterial communication. Cell 144:590–600
Ettwig FK et al (2010) Nitrite-driven anaerobic methane oxidation by
oxygenic bacteria. Nature 464:543–547
Fuchs BM et al (2007) Characterization of a marine gammaproteobacterium capable of aerobic anoxygenic photosynthesis. Proc Natl
Acad Sci USA 104:2891–2896
70
R. Matheron and P. Caumette