Title: Dr. Alvin Fox
1Nutrition, Growth and Metabolism, Lecture 26
Dr. Alvin Fox
2KEY TERMS
Obligate aerobe Obligate anaerobe Aerotolerant
anaerobe Facultative anaerobe Microaerophilic Side
rophore Mesophile Thermophile Psychrophile Generat
ion time
Growth curve Glycolysis Fermentation Anaerobic
respiration Aerobic respiration Tricarboxylic
acid (TCA) cycle or Krebs cycle Oxidative
phosphorylation Ubiquinone Glyoxylate pathway
3Bacterial requirements for growth
- oxygen (or absence)
- energy
- nutrients
- optimal temperature
- optimal pH
4Obligate aerobes
- grow in presence of oxygen
- no fermentation
- oxidative phosphorylation
5Obligate anaerobes
- no oxidative phosphorylation
- fermentation
- killed by oxygen
- lack certain enzymes
- superoxide dismutase
- O2-2H H2O2
- catalase
- H2O2 H20 O2
- peroxidase
- H2O2 NADH H H20 NAD
-
6Aerotolerant anaerobes
- respire anaerobically
- not killed by oxygen
7Facultative anaerobes
- fermentation
- aerobic respiration
- survive in oxygen
8Microaerophilic bacteria
- grow
- low oxygen
- killed
- high oxygen
9Optimal growth temperature
- Mesophiles
- human body temperature
- pathogens
- opportunists
- pyschrophile
- close to freezing
- thermophile
- close to boiling
10pH
- Many grow best at neutral pH
- Some can survive/grow
- - acid
- - alkali
11Nutrient Requirements
- Carbon
- Nitrogen
- Phosphorus
- Sulfur
- Metal ions (e.g. iron)
12Siderophores (S)
Receptor
Fe 2/S
Fe 2/S
13Measuring bacterial mass (live dead) in liquid
culture
Turbidity (Cloudiness)
14Measuring viable bacteria
Colony forming units
colony
15Growth Curve
Stationary
TURBIDITY (cloudiness)
Autolysis
Log
Lag
TIME
16Growth Curve
Stationary
COLONY FORMING UNITS
Death
Log
Lag
TIME
17Generation time
- time for bacterial mass to double
- Example
- 100 bacteria present at time 0
- If generation time is 2 hr
- After 8 hr mass 100 x 24
18SUGAR CATABOLISM
- Glycolysis
- Embden Meyerhof Parnas Pathway
- most bacteria
- also animals and plants
19Other pathways for catabolizing sugars
- Pentose phosphate pathway (hexose monophosphate
shunt) - generates NADPH
- common in plants and animals
- Entner Doudoroff Pathway
- a few bacterial species
20 Glycolysis
NAD
NADH
Glucose
Pyruvate
C6
C3
ADP
ATP
21Fermentation
NADH
NAD
Pyruvate
Short chain alcohols, fatty acids
(C3)
(C2-C4)
22Anaerobic Respiration Glycolysis Fermentation
NAD
NADH
ATP
NAD
NADH
23Krebs Cycle (C4-C6 intermediate compounds)
NAD
NADH
3CO2
Pyruvate
(C3)
(C1)
Oxidative phosphorylation
NADH
NAD
O2
H2O
ADP
ATP
24Aerobic Respiration Glycolysis Krebs
Cycle/oxidative phosphorylation
- Pyruvate to CO2
- NAD to NADH
- glycolysis
- Krebs cycle
- Oxidative phosphorylation
- NADH to NAD
- ADP to ATP
25Oxidative phosphylation
- converts O2 to H20 (oxidative)
- converts ADP to ATP (phosphorylation)
- electron transport chain
- ubiquinones/cytochrome intermediates
26The Krebs cycle
X
C
Isocitrate
C2
Acetate
-CO2 NADH
C6
Citrate
-CO2
Alpha-keto glutarate
C4
Oxaloacetate
Pyruvate
-CO2 NADH
x
C
Succinate
Malate
Fumarate
27Krebs Cycle - sugar as sole carbon source
Acetate
Krebs cycle
-CO2
Oxalo acetate
Pyruvate
C2
Citrate
C4
C
C6
C3
-2CO2
BIOSYNTHESIS
ENERGY STORAGE
X
Oxalo acetate
Aspartic acid
CO2
Oxaloacetate
Pyruvate
C4
C
C3
28Krebs Cycle fatty acids as sole carbon source
ENERGY
Acetate
Krebs cycle
Fatty acids
Oxalo acetate
Citrate
BIOSYNTHESIS
x
-2CO2
Oxalo acetate
Aspartic acid
C2
Isocitrate
Glyoxylate
Succinate
C2
-2CO2
Acetate
Krebs cycle
C4
C6
Malate
C4
29The Glyoxylate and Krebs cycles
Isocitrate
Citrate
1
Alpha-keto glutarate
Glyoxylate
Oxaloacetate
2
Acetate
Succinate
Malate
Fumarate
Krebs and Glyoxylate cycles
Krebs cycle only
Glyoxylate cycle only
30- Krebs Cycle
- biosynthetic
- energy storage
- Removal of intermediates
- must be replenished
- Unique enzymatic replenishment pathways
- sugars
- fatty acids