Bio 230 - Microbiology - Spring 2010
Study Guide 05
Metabolism"
* From the Greek work for "change"
* Sum of all the chemical reactions that convert nutrients into
energy and complex molecules required for living systems
* Between nutrients (raw materials) and end products
(complex bio-molecules) are many intermediate
compounds. Thus, metabolism is also referred to as
intermediary metabolism
Dr. Michael Blaber
Time-energy graphs of an exergonic reaction.
Images from Purves et al., Life: The Science of Biology, 4th Edition
?G0 = -nF?E0
B. methanol/NO3- (producing NO2- )
?E0= 0.80
n=6
?G0 = 4.80
A. H2 /Fe+3
?E0= 1.18
n=1
?G0 = 1.18
C. Fe+2/O2
?E0= 0.06
n=1
?G0 = 0.06
Substrate level phosphorylation (SLP)
The simplest, oldest and least-evolved way to make ATP
The Embden Meyerhof Pathway for Glucose Dissimilation.
Entner-Doudoroff Pathway
Glucose -------> 2 ethanol + 2 CO2 + 1 ATP (net)
http://www.geneseo.edu/~simon/bio230/files/J_Bact_180_3495.pdf
Oxidative Pathways of Glycolysis Employed by Various Bacteria
EmbdenMeyerhof
pathway
Phosphoketolase
(heterolactic) pathway
EntnerDoudoroff
pathway
Acetobacter aceti
-
+
-
Agrobacterium tumefaciens
-
-
+
Azotobacter vinelandii
-
-
+
major
+
minor
-
-
Lactobacillus acidophilus
+
-
-
Leuconostoc mesenteroides
-
+
-
Pseudomonas aeruginosa
-
-
+
minor
-
major
-
-
+
Bacterium
Bacillus subtilis
Escherichia coli
Vibrio cholerae
Zymomonas mobilis
Glyoxylate Cycle
Used by plants and bacteria
to convert two acetyl-CoA
molecules into oxaloacetate.
This allows these organisms
to grow using acetate as the
sole carbon source. This is
important for seedlings
which have large reserves of
fatty acids but cannot yet
photosynthesize. The cycle
uses some of the enzymes of
the TCA cycle, but instead
of converting the acetyl-CoA
to carbon dioxide and
energy, it forms a new
molecule of oxaloacetate:
Fermentations in bacteria that proceed through the
Embden-Meyerhof pathway.
The heterolactic
(phosphoketolase)
pathway of
fermentation
Compared to the
EmbdenMeyerhof
pathway it differs
in the early steps
before the
cleavage of the
molecule.
Glucose -------> Lactic acid + ethanol + CO2 + 1 ATP (net).
End Yield Products of Microbial Fermentation
Pathway
Key enzyme
Ethanol
Lactic
CO2 ATP
Acid
Embden-Meyerhof
fructose 1,6-diP aldolase
Saccharomyces
2
0
2
2
Embden-Meyerhof
fructose 1,6-diP aldolase
Lactobacillus
0
2
0
2
Heterolactic
Streptococcus
phosphoketolase
1
1
1
1
Entner-Doudoroff
Zymomonas
KDPG aldolase
2
0
2
1
Syntrophy. The characteristic of syntrophy refers to the arrangement
of two or more microoganisms living in a common niche where the
waste products of one microorganism serve as substrates for the other.
The End