methanogenic archaebacteria
TRANSCRIPT
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Sabyasachi Dasgupta
BTB/10/010
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They are the Oldest living Organisms that came into being 3.7
million years ago when Earth was not quite pleasant
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They Have a 3 Layered (Gramve ) or 2 layered(Gram +ve) Cell wall
They dont have any membrane bound organelles like mitochondria or
lysosomes
They have DNA spread into the cytoplasm condensed in an area called
Nucleoid
They have Small packets of DNA
called Plasmids
They have 16s rRNA Subunit
Have Pilli, Fimbriae and Flagella
Can thrive through extremes of
conditions
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Ms Residence
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CO2
H2Formate
Fermentation
CH4
CO2
+
Hence M family is
referred to as
Methanogens
because they
produce Methane.
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Group I
Group II
Group III
Methanobacteriu
m
Methanobrevibac
ter
Methanococcus
Methanospirilliu
m
Methanosarcina
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Genus: Methanobacterium Genus: Methanobrevibacter
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Mr. Methanobacterium byrantii
of
genus Methanobacterium
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Most Chemically Complex Cell wallamong Group I members
Tough and rigid composed of
Pseudomurein
Lacks D-Amino acids that is present
in the peptidoglycan of eubacteria
Resembles those of Gram +veBacteria and hence gives the +ve
result for Gram Reaction
It is Thick and Homogenous
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C20 diether
C40tetra
ether
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Morphologically rodshaped and filamentous32 50% G+C Stain +ve in GramReactionUses H2 + CO2 andformate asMethanogenic Substrates.
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Structure of Pseudomurein
Tough and rigid 3 layer cell wall.
Lacks D-Amino acids that is present
in the peptidoglycan of eubacteria
Resembles those of Gram +veBacteria and hence gives the +ve
result for Gram Reaction
It is Thick and Homogenous
Pseudomurein is present in the
innermost layer. The chemical
composition of the outer layers is
not yet known.
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C20 diether
C40tetra
ether
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27 32% G+C Stain +ve in Gram
ReactionUses H2 + CO2 only asMethanogenic Substrates. Straight or circular rodshapedMethanobrevibacter smithii.
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Flexible single layered cell wall
Its entirely made up of Proteins
Resembles those of Gram -ve
Bacteria and hence gives theve
strain result for Gram Reaction
It is Homogenous
Traces of Glucosamine is present
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C20 diether is the only component present as lipids in methanococcus
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30 32% G+C Stain +ve in GramReactionUses H2 + CO2 andformate asMethanogenic Substrates. Shaped as irregularshaped spheres (cocci)
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Group III
Genus Methanospirillium Genus Methanosarcina
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PPlug,
SSheath,
WCell wall,
AM Amorphous Matrix
It has the most complex
Cell Wall among theMethanogens
Two layered Cell Wall
Outer Wall made of
protein resistant toproteases and
detergents(SDS)
Sheath envelopes the
cells in a helical
trichome
Inner Layer is electron rich
Polar flagella may be present at both ends
allowing limited movements
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C20 diether
C40tetra
ether
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45 47% G+C Stain -ve in Gram
ReactionUses H2 + CO2 andFormate as
Methanogenic SubstrateCurved Rod or Spiralshaped
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Single thick and rigid Cell Wall
Made of heteropolysaccharides
which consists of galactosamine,
neutral sugars and muramic acids.
The Cell wall is acidic in Nature
Dont posses Envelope but cell wall is
laminar
Some contain a methanochondroitin
covering exterior to the S-Layer and
is sometimes called matrix.
The matrix plays an important role in
cell adhesion
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C20 diether is the only component present as lipids in methanococcus
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38 51% G+C Stain +ve in GramReactionUses H2 + CO2 ,CH3OH, Methylamineand Acetate as
Methanogenic SubstrateObserved as IrregularSpherical packets
M h
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MethanogenesisIt is the process of formation of Methane (CH4) by Methanogenic Bacteria from
substrates such as :i) H2
ii) CO2iii) Methanol
iv) Acetate
v) Formate etc.
With the help of Various Co-Factors and Co-Enzymes such as:
i) F420
ii) Coenzyme B
iii) Coenzyme M
iv) Methanofuran
v) Methanopterin
Two complex pathways exist that can be somewhat simplified as:
CO2 + 4 H2 CH4 + 2H2O
CH3COOH CH4 + CO2
M P
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Methanogenesis Pathway
Cofactor abbreviations:
1) Tetrahydromethanopterin
(H4MPT)
2) MethanopterinMPT
3) MethanofuranMFR
4) 2-mercaptoethanesulfonic
acid or coenzyme M
(CoM).
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The mechanism Relating Methanogenesis to ATP synthesis is still undiscovered
Classical Electron Transport chain is not involved
Energy Conservation is though to be mediated by a Chemiosmotic Membrane Potential
On collapsing the potential ATP concentration diminishes rapidly
Energy Yielding Reactions Performed by the Methanogens:
4H2 + HCO3- + H+ CH4 + 3H2O -33
4HCOO- + 4H+ CH4 + 3CO2 + 2H2O -35
4CH3OH 3CH2 + CO2 + H2O -76
4CH3NH3+ + 3H2O 3CH4 + 4NH4
+ + HCO3- + H+ -75
CH3COO- + H+ CH4 + CO2 -9
Reaction G (kcal/Mole)
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Out
InIn
Out
Cell Membrane2e-Hydrogenase
F420(Reduced)
F420(Oxidized)
2H+
H2
2H+
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In addition to oxidation of H2 coupled with the
reduction of CO2 methanogens are capable ofusing elemental sulfur as the electron acceptor
This process is called Sulphur Reduction
Methanogens belonging to Groups I and II cease
Methanogenesis when exposed to a sulphur
gradient and grown in its presence.
Group III methanogens continue Methanogenesis
simultaneously along with Sulphur Reduction
CO2 is their sole Carbon source and are hence
autotrophs
They are highly reducing in nature
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Actions of the M makes us do this but CH4
Can be very efficient and useful as a biofuel and waste treatment
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(Workplace of the M. Family)
Heating Coil
What does he do
In here???
Mr. Methanospirillium hungarii
Stays & Works
in here
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Street Lights
Runs on CH4
VolkswagenCH4 run vehicle
Mirant Kendall Regeneration Station
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Bibliography
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Bibliography
Textual References for this presentation on Ms Family has been collected from: i) Microbiology Lansing M. Prescottii) Wikipedia www.wikipedia.org
Visual and Photographic References have been taken from:i) www.wadsworth.org/resnres/bios/macario/ii) www.corbisimages.com
http://www.wikipedia.org/http://www.wikipedia.org/ -
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