"A lithotroph is an organism that uses
an inorganic substrate (usually of mineral origin) to obtain reducing equivalents
for use in biosynthesis (e.g., carbon dioxide fixation) or energy conservation
via aerobic or anaerobic respiration. Known lithotrophs are exclusively
microbes; No known macrofauna possesses the ability to utilize inorganic
compounds as energy sources."
"Here are a few examples of lithotrophic
pathways, any of which may use oxygen or sulfur as electron acceptor:
* Iron bacteria oxidize
ferrous iron (Fe2+) into ferric iron (Fe3+)
* Nitrifying bacteria
oxidize ammonia (NH3) into nitrite (NO?2) or, alternatively, nitrite (NO?2)
into nitrate (NO?3).
* Purple sulfur bacteria
and some chemolithotrophs oxidize sulfide (S2?) into sulfur (S0). Here
oxygen is the electron acceptor.
* Sulfur bacteria use
oxidized sulfur compounds to produce sulfide. They also can grow on a number
of oxidized or partly oxidized sulfur compounds (e.g. sulfate (SO2?4),
thiosulfate (S2O2?3), thionates, polysulfides, sulfite). Here, sulfur is
the electron acceptor.
* Hydrogen bacteria
oxidize hydrogen to water.
bacteria oxidise carbon monoxide to carbon dioxide.
In the following examples, compounds other
than oxygen are used as electron acceptors:
* Methanogens are Archaea
capable of oxidising hydrogen, reducing carbon dioxide to methane.
* Thiobacillus denitrificans
is one of many known sulfur bacteria, oxidizing reduced sulfur compounds
with nitrate instead of oxygen.
* The recently discovered
Anammox bacteria oxidise ammonia with nitrite as electron acceptor to produce
* Phosphite bacteria
oxidize phosphite into phosphate. They use sulfate as electron acceptor,
and reduce it into sulfide."
"Deep Sea Vent Communities: Did Life
Originate in the Abyss?"
"Chemolithotrophs use the above inorganic
compounds for aerobic or anaerobic
respiration. The energy produced by
the oxidation of these compounds is enough
for ATP production."
"Phototrophs use light as energy source.
These bacteria are photosynthetic; photolithotrophic bacteria are found
in the purple bacteria (e. g., Chromatiaceae), green bacteria (Chlorobiaceae
and Chloroflexi) and Cyanobacteria"
"Photoautotrophs are organisms (usually
plants) that carry out photosynthesis to acquire energy. Energy from sunlight
is used to convert carbon dioxide and water into organic materials to be
used in cellular functions such as biosynthesis and respiration.