2. ARCHAEBACTERIA
• Archaebacteria are the oldest organism living on
Earth. They are unicellular prokaryotes- microbes
without cell nucleus and any other membrane-
bound organelles in their cells- and belong to the
kingdom,Archae .They were first discovered in
1977 by Carl Woose and George E. Fox and
classified as bacteria. Most archaebacteria appear
like bacteria, when observed under the microscope.
However, ther are quite different from bacteria and
eukaryotes.
3. • Archaebacteria are found in very
harsh conditions such as in the
volcanic vents or at the bottom of the
sea. They can easily survive in such
extreme environment as sea vents
releasing sulfide-rich gases,hot
springs or boiling mud around
volcanoes
4. SUB-GROUPS OF ARCHAEBACTERIA
Methanogens-They produce marsh gas that can be
observed as bubbles in stagnant water. They are also
present in the gut of cattle and termites, since there is no
oxygen there. Methanogens use carbon dioxide as an
electron acceptor to oxidize hydrogen using co-enzymes
like co-enzyme M and methanofuran. These co-enzymes
are very unique to archaebacteria. These bacteria are
rod shaped or spherical, and can be gram positive as
well as negative.
5.
6. Halophiles - are bacteria that can survive in 10 times
the concentration of salt present in sea.Halobacter uses
photophosphorylation for metabolism. They use light
activated ion pumps like bacteriorhodopsin and
halorhodopsin for generation of ion gradients to pump out
ions across the plasma membrane. The energy that is
stored in the electrochemical gradients is converted to
ATP by ATP synthase. They contain bacteriorhodopsin, a
red or orange pigment.
7.
8. Thermoacidophiles -are organisms that can
survive in extremely high temperatures and low
pH. They can survive in 100° Celsius with a
pH of 2. Most of these organisms are
anaerobic in nature.
9.
10. ARCHABECTERIA ARE CLASSIFIED
INTO THE FOLLOWING PHYLA
Phylum Euryarcheota: This is the most studied
division of archaea. It is highly diverse and include
methanogens, which produce methane and are
often found in intestines, halobacteria, which
survive extreme concentrations of salt, and some
extremely thermophilic aerobes and anaerobes.
11. EXAMPLES:
• Methanobrevibacter
smithii -
is a genus of the
Methanobacteriaceae.
The species within
Methanobacteriaceae are
strictly anaerobic aechaea
that produce methane, for
the most part through the
reduction of carbon
12. • Halobacterium
salinarum - is an
extremely halophilic marine
Gram-negative obligate
aerobic archaeon. Despite its
name, this is not a bacterium,
but rather a member of the
domain Archaea. It is found in
salted fish,hides,hypersaline
lakes, and salterns.
13. Phylum Crenarchaeota: It includes
thermophiles and hyperthermophiles.
This archebacteria are mostly found
in the marine environment.
16. Phylum Korarchaeota: This division
consists of hyperthermophiles found in
high temperature hydrothermal
environment.
17. EXAMPLE:
• Candidatus Korarchaeum
Cryptofilum - The archaeal
division Korarchaeota
represents an earlu divergent
branch of the Archaea. This is
a hyperthermophilic archaeon
which has not yet been
isolated in pure culture.
19. EXAMPLES:
• Nitrosopumilus
maritimus - it is one of the
smallest living organisms
at 0.2 micrometers in
diameter.It is capable of
oxidizing ammonia at
levels as slow as 10
nanomolar, near the limit
to sustain its life.
20. • Nitrososphaera Garnesis - It
is observed in small abnormal
cocci groupings and uses its
flagella to move
chhemotaxis.It has a cell
membrane composed of
crenarchaeol, its isomer and a
distinct glycerol dialkyl
glycerol tetraether which is
significan in identifying
ammonia-oxidizing archaea.
21. Phylum Nanoarchaeota - This phylum has a
single representative member named
Nanoarchaeum equitans. This unusual
archebaterium is an obligate symbiont of
another archaea belonging to the genus
Ignicoccus.
22. EXAMPLE:
• Nanoarchaeum
equitans - is a species
of marine Archaea that
was discovered in 2002 in
a hydrothermal vent off the
coast of Iceland on the
Kolbeinsey Ridge by Karl
Stetter.It has been
proposed as the first
species in a new phylum.
24. • They have phylogenetic importance that
helps in studying their homology and
establish their phylogeny.
• Their ability to tolerate extreme conditions
helps researchers learn about the climatic
conditions, environment and their survival
on ancient earth.
25. • Methanogens can grow in biogas fermentors
and decompose cow dung into methane gas
as a by-product. Thus, they are used for
production of domestic gas for cooking.
• Organisms like Methanobacterium
ruminantium are present in the guts of
ruminating animals, helping them digest the
cellulose.
26. • Archaebacteria are also used to synthesize
thermophilic enzymes, restriction enzymes
and are also used as biosensors.
• Archaebacteria have an important role in
many chemical cycles, like carbon cycle,
nitrogen cycle, sulfur cycle.
27. • Due to their extremophilic nature,
archaebacteria have proven to be of great
help in the field of Bioechnology, by
helping in the production of enzymes that
work at very high temperatures, as well as
in the production of some antibiotics.
