Lecture 11 – BIMM120.SP11
LECTURE 10 – May 05, 2011
Metabolic Diversity I: Fermentation & Respiration
(BLACK = this lecture /
BLUE = different lecture
/
RED = not covered in lecture
)
Chapter 5 – Nutrition, Culture, and Metabolism of Microorganisms
(pp.122-125)
IV. Essentials of Catabolism
5.9
Energy Conservation
•
Substrate-Level Phosphorylation and Oxidative Phosphorylation
o
In fermentation, ATP is produced by
substrate-level phosphorylation
o
In
oxidative phosphorylation
ATP is produced at the expense of the proton
motive force
5.10
Glycolysis as an Example of Fermentation
•
Stage I: Preparatory Reactions
o
Glucose is phosphorylated by ATP
o
Fructose 16 biphosphate is split into two 3-carbon molecules
•
Stage II: The Production of NADH, ATP, and Pyruvate
o
Glyceraldehyde 3-phosphate is oxidized
o
NAD
+
is reduced to NADH
o
Pyruvate and ATP are produced
•
Stage III: Consumption of NADH and the Production of Fermentation Products
o
The NADH produced in glycolysis must be oxidized back to NAD
+
in order
for glycolysis to continue
•
Glucose Fermentation: Net and Practical Results
o
During glycolysis glucose is consumed, two ATPs are made, and different
fermentation products are generated
Microbial Sidebar:
The Products of Yeast Fermentation & the Pasteur Effect (pg 125)
Chapter 21 – Metabolic Diversity: Catabolism of Organic Compounds
(pp.613-618;
622-630)
I. Fermentation
21.1
Fermentations:
Energetic and Redox Considerations
•
Fermentations
o
Many microbial habitats are
anoxic
o
If adequate supplies of electron acceptors such as NO
3
-
, Fe
3+
,
and others are
not available in anoxic microbial habitats, organic compounds are catabolized
by
fermentation
o
In fermentation, ATP synthesis usually occurs by
substrate-level
phosphorylation
•
Energy-Rich Compounds and Substrate-Level Phosphorylation
1
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Lecture 11 – BIMM120.SP11
o
Energy conservation by substrate-level phosphorylation occurs in many
different ways
o
Central to ATP synthesis is the production of
energy-rich compounds
. These
are organic compounds that contain an energy-rich phosphate bond or a
molecule of coenzyme-A
•
Oxidation-Reduction Balance, H
2
, and Acetate Production
o
There must be an oxidation-reduction (redox) balance in any fermentation
o
In a number of fermentations, electron balance is maintained by the
production of molecular hydrogen (H
2
)
o
The production of H
2
is associated with the activity of an iron-sulfur protein
called
ferredoxin
o
The transfer of electrons from ferredoxin to H
+
is catalyzed by the enzyme
hydrogenase
o

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- Spring '08
- Larsen
- Bacteria, Cellular Respiration, Adenosine triphosphate, ELECTRON ACCEPTORS, Methanogenesis, Energetics of Sulfate Reduction
-
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