Methanogens and Ruminants
Overview
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Domain Archaea is divided into 3 subgroups:
Extreme halophiles
 Extreme thermophiles
 Methanogens
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Methanogens are microorganisms that
produce methane as a byproduct of its
metabolism.
Methane molecules
What are methanogens?
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Use H2 to reduce CO2 to methane (CH4)
Usually coccoid or rod-shaped
Obligate anaerobes
Although they can’t function with O2, they can
sustain oxygen stresses for prolonged times
Over 50 species have been identified
String of methanogen bacteria
Where are methanogens found?
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Wetlands, where
generated methane is
called marsh gas
Guts of animals like
ruminants (cattle,
sheep, goats) and
humans
Methanogens might
be responsible for
CH4 found in the
atmosphere of Mars
What is a ruminant?

Animal with a stomach that has multiple
compartments, which let it break down celluloserich foods (with the help of methanogens); it
partially regurgitates its food (called cud) to help
the digestive process
*Ruminants often have a thoughtful
expression on their faces while they
chew their cuds. This explains the
origins of the name, which is derived
from the Latin ruminare, the same
root for the word “ruminate” as in
“to think.”
(Methanogens found in the rumen)
Importance
Methanogens are important
decomposers used in sewage treatment
 Use methane gas as biofuel
 Methane gas is a relatively potent
greenhouse gas, thus contributing to
global warming
 http://www.youtube.com/watch?v=mO
ZKVPtuXWU
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Review Questions
1.
2.
3.
4.
5.
6.
Name three places methanogens are found.
T/F- Methanogens can use O2 if it’s present.
Where are methanogens found in the
ruminant’s digestive tracts?
Why can animals like cows break down
cellulose and not humans?
Describe the shape of methanogens.
List two ways to use methanogens.
Answers to Review Questions
1.
2.
3.
4.
5.
6.
Wetlands, guts of ruminants, humans.
False.
In the rumen.
Ruminants have several compartments in
their stomachs to thoroughly digest their
food…whereas we don’t.
Coccoid or rod-shaped.
Break down wastes in sewage treatment
and use the methane produced as biofuel.