Microbial Metabolism
•Metabolism and Energy
•Catabolism vs Anabolism; Exergonic vs Endergonic rxns
•Using ATP to make endergonic rxns run
•Enzymes as Biological Catalysts
•Lowering of Activation Energy
•Specificity, recyclability
•Factors which affect Enzymatic Rate (pH, temp, inhib.)
•Metabolic Control
•Cellular Respiration: Oxidative Catabolism
•Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
•C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
•Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
•Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
•Electron Transport Chain (Cashing in on e-)
•FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
•Terminal aerobic electron acceptor O2--->H2O
•Anaerobic bacteria use nitrate, sulfate, carbon dioxide
•Fermentation is not anaerobic respiration
•Performed by facultative anaerobes
•Restart glycolysis by recycling NADH->NAD+ in side rxns
•Acid and/or Gas common (pH drop)
•Alcohol Fermentation (yeast, some bacteria)
•Ethanol and carbon dioxide produced
•Lactic Acid Fermentation (bacteria, muscles)
•Heterolactic Fermentation (several bacteria)
•Acetoin: a neutral product in VP test
•Use of Other Food Molecules for Energy
•Lipid Catabolism to Acetyl CoA
•Protein Catabolism to Kreb’s Cycle Molecules
•Deamination, Ammonium, and pH rise
Metabolism: Breakdown of Food Fuels Construction of Biomolecules
Food molecules (high energy)
Breakdown
(Catabolism)
Complex biomolecules (high energy)
Energy from chemical bonds  Usable cellular energy (ATP)
Waste molecules (low energy)
Construction/
Synthesis
(Anabolism)
Simple molecules (low energy)
Cellular Reactions Either Use or Liberate Energy
•
Catabolic/Breakdown Reactions release energy
o Molecules become more disorganized or less structured
X
+
Y
+
Z
•
Anabolic/Buildup Reactions absorb energy
o Molecules become more ordered and complex
o ATP needed to power endothermic reactions
A
+
B
+ ATP
C
Both Breakdown and Buildup Reactions Have Activation Energies
X + Y
Z
+
Energy Level
Breakdown Reactions Release Energy: Exergonic/exothermic
Activation
Z
Energy
X+Y
Time
Buildup Reactions Absorb or Require Energy: Endergonic/endothermic
C
+ ATP
C
Energy Level
A + B
Activation
A+ B
Time
Energy
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
Electron Transport Chain (Cashing in on e-)
FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Lactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise
Activation Energy
• Energy needed to allow the
reactants to form products
• Necessary for a chemical
reaction to proceed
• Activation energy is needed
even for breakdown reaction
to get them going
•
Energy Level
• Activation energy
Activation
Z
Energy
X+Y
Time
In the laboratory, we heat the reactants in order to provide
activation energy for a chemical reaction
•
Inside the cell, a different mechanism is required as heating up
the reactants is not possible
Lower the energy required for the reaction
Enzymes Lower Activation Energy and Speed Up Reactions
Figure 5.8
Enzymes Are Biological Catalysts
Figure 5.2
Enzymes
Figure 5.3
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
Electron Transport Chain (Cashing in on e-)
FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Lactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise
Factors Influencing Enzyme Activity
• Enzymes can be denatured by temperature and pH
Figure 5.6
Enzymes Become Non-Functional at pH Extremes and High Temperatures
H
H
OH-
+
+
(products formed per second)
Enzymatic rate
+
H
+
H
H
+
H
+
OH-
+
encounter enzyme
less often
OHOH-
H
+
H
OH-
H
+
+
OH-
H
OH-
+
H H
+
+
H
OH-
+
0
= folded, functional enzyme
= denatured, non-functional enzyme
Enzyme within
Enzyme from
Reaction
rate is slow
a body cell
OH
at cold temperatures
hot springs
because
molecules
bacterium
OH
2
4
6
8 10
pH (in pH units)
(products formed per second)
H
Enzyme within
a body cell
12
Enzymatic rate
Stomach
enzyme
10
20
30 40 50 60
Temperature (oC)
70
Factors Influencing Enzyme Activity
• Competitive inhibition
Figure 5.7a, b
Factors Influencing Enzyme Activity
• Noncompetitive inhibition
ATP, pyruvate, end
amino acid
Figure 5.7a, c
Factors Influencing Enzyme Activity
• Feedback
inhibition
Figure 5.8
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
Electron Transport Chain (Cashing in on e-)
FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Lactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise
Oxidation-Reduction
• Oxidation is the removal of electrons.
• Reduction is the gain of electrons.
• Redox reaction is an oxidation reaction paired with a
reduction reaction.
OIL RIG: Oxidation is loss of e-, reduction is gain of e-
Figure 5.9
Oxidation-Reduction
• In biological systems, the electrons are often
associated with hydrogen atoms. Biological oxidations
are often dehydrogenations.
Or FAD+
FADH2
Sugars, amino acids,
fatty acids
Figure 5.10
The Energy Stored in ATP Can Be Used to Perform Work in the Cell
• The energy released by ATP breaking down into
ADP and P can power a variety of needs in the cell
Energized ATP:
ADP
Discharged ATP:
ADP
Powering the synthesis of
molecule Z:
P
P
X
+
Y
Z
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
Glycolysis (6C glucose--> 2 pyruvate + 2NADH + 2ATP
Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
Electron Transport Chain and ATP Generation FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Lactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise
Aerobic Cellular Respiration: Converting Sugar to
COATP
2
C6H12O6 + O2
sugar
oxygen
glucose
CO2 + H2O + 36ATP
carbon dioxide oxygen
usable energy
CO2
NAD+
Glycolysis
2 ATP
NADH
2 pyruvates
Cell membrane
CO2
Krebs Cycle
H+ +
H
H+
H+
Electron
Transport
H+
Chain and
H+
ATP
+
+ H
H
Synthase
H+
(Ox. Phos.)
NADH, FADH2
NAD, FAD+
O2
H 2O
H+
~ 30 ATP
H+
H+
ATP Synthase
ATP fuels
construction/synthe
sis reactions inside
the cell
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
1. Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
2. Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
3. Electron Transport Chain (Cashing in on e-)
FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Lactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise
Respiration
• Aerobic respiration: The final electron acceptor in the
electron transport chain is molecular oxygen (O2) in
aerobes.
• Anaerobic respiration: The final electron acceptor in
the electron transport chain is not O2. Yields less
energy than aerobic respiration because only part of
the Krebs cycles operations under anaerobic
conditions. Obligate anaerobes perform anaerobic
respiration.
• Fermentation: Glycolysis is restarted as NADH is
recycled into NAD+. Pyruvate is reduced when
electrons are added to it; acids, ethanol and CO2 are
common products. Facultative anaerobes perform
fermentation in addition to aerobic respiration.
Anaerobic respiration by Obligate Anaerobes
Terminal electron acceptor
NO3– (nitrate)
Products
NO2–, NH3, N2 (nitrite, ammonia,
and nitrogen gas)
SO4– (sulfate)
H2S (hydrogen sulfide)
CO32 – (carbonate)
CH4 (methane)
Peee-ewe! (stinky)
H+ +
H
H+
H+
Electron
Transport
H+
Chain and
H+
ATP
H+
+
H
Synthase
H+
(Ox. Phos.)
NADH, FADH2
NAD, FAD+
O2
H 2O
H+
~ 30 ATP
H+
H+
ATP Synthase
Two Net ATP are Made in Glycolysis by Substrate Level Phosphorylation
1 glucose
2 (net) ATP made by
substrate-level
phosphorylation
rather than by
oxidative
phosphorylation
2 pyruvate
1 glucose
Fermentation by Facultative Anaerobes
• NADH is recycled to NAD+ in
order to keep glycolysis
running
• Alcohol fermentation
Produces ethyl alcohol + CO2
• Lactic acid fermentation
produces lactic acid.
• Homolactic fermentation
produces lactic acid only.
• Heterolactic fermentation
produces lactic acid and
other compounds.
Figure 5.19
Fermentation Products Are Mostly Acids with Some Gases
Figure 5.18b
Fermentation (Change to Yellow Means Acid is Present; Durham Tubes
Collect Gas)
Figure 5.23
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
Electron Transport Chain (Cashing in on e-)
FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Lactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise
Lipid Catabolism
CO2
glucose
C
2 ATP
2 pyruvates
C
Krebs Cycle
H+ +
H
H+
NADH, FADH2
H+
NAD, FAD+
H+
O2
H+
H+
H 2O
~ 30 ATP
H+
H+
H+
H+
H+
ATP Synthase
Figure 5.20
Protein Catabolism Produces Alkaline Ammonium
Protein
Extracellular proteases
Deamination, decarboxylation, dehydrogenation
NH4+
CO2
H2
Amino acids (Peptone)
Organic acid
Krebs cycle
Biochemical tests and Dichotomous Keys Are Used to ID Prokaryotes
Figure 10.8
Microbial Metabolism
Metabolism and Energy
Catabolism vs Anabolism; Exergonic vs Endergonic rxns
Using ATP to make endergonic rxns run
Enzymes as Biological Catalysts
Lowering of Activation Energy
Specificity, recyclability
Factors which affect Enzymatic Rate (pH, temp, inhib.)
Metabolic Control
Cellular Respiration: Oxidative Catabolism
Oxidation-Reduction Reactions(NAD+, FAD+ trucks)
C6H12O6 + 6O2 -->6CO2 + 6H2O + Energy (ATP)
Glycolysis (6C glucose--> 2 pyruvate + 2NADH +2ATP
Krebs Cycle (2 pyruvate-->6CO2 + 8NADH +2FADH2 + 2ATP
Electron Transport Chain (Cashing in on e-)
FADH2 + NADH + O2 --> lots of ATP + H2O + NAD+ + FAD+
Terminal aerobic electron acceptor O2--->H2O
Anaerobic bacteria use nitrate, sulfate, carbon dioxide
Fermentation is not anaerobic respiration
Performed by facultative anaerobes
Restart glycolysis by recycling NADH->NAD+ in side rxns
Acid and/or Gas common (pH drop)
Alcohol Fermentation (yeast, some bacteria)
Ethanol and carbon dioxide produced
Homolacticactic Acid Fermentation (bacteria, muscles)
Heterolactic Fermentation (several bacteria)
Acetoin: a neutral product in VP test
Use of Other Food Molecules for Energy
Lipid Catabolism to Acetyl CoA
Protein Catabolism to Kreb’s Cycle Molecules
Deamination, Ammonium, and pH rise