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Nutrition, Growth and Metabolism, Lecture 26. Dr. Alvin Fox. KEY TERMS . Obligate aerobe Obligate anaerobe Aerotolerant anaerobe Facultative anaerobe Microaerophilic Siderophore Mesophile Thermophile Psychrophile Generation time. Growth curve Glycolysis Fermentation

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slide1

Nutrition, Growth and Metabolism,

Lecture 26

Dr. Alvin Fox

key terms
KEY TERMS

Obligate aerobe

Obligate anaerobe

Aerotolerant anaerobe

Facultative anaerobe

Microaerophilic

Siderophore

Mesophile

Thermophile

Psychrophile

Generation time

Growth curve

Glycolysis

Fermentation

Anaerobic respiration

Aerobic respiration

Tricarboxylic acid (TCA)

cycle or Krebs cycle

Oxidative phosphorylation

Ubiquinone

Glyoxylate pathway

bacterial requirements for growth
Bacterial requirements for growth
  • oxygen (or absence)
  • energy
  • nutrients
  • optimal temperature
  • optimal pH
obligate aerobes
Obligate aerobes
  • grow in presence of oxygen
  • no fermentation
  • oxidative phosphorylation
obligate anaerobes
Obligate 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
aerotolerant anaerobes
Aerotolerant anaerobes
  • respire anaerobically
  • not killed by oxygen
facultative anaerobes
Facultative anaerobes
  • fermentation
  • aerobic respiration
  • survive in oxygen
microaerophilic bacteria
Microaerophilic bacteria
  • grow
    • low oxygen
  • killed
    • high oxygen
optimal growth temperature
Optimal growth temperature
  • Mesophiles:
    • human body temperature
      • pathogens
      • opportunists
  • pyschrophile
    • close to freezing
  • thermophile
    • close to boiling
slide10
pH
  • Many grow best at neutral pH
  • Some can survive/grow
    • - acid
    • - alkali
nutrient requirements
Nutrient Requirements
  • Carbon
  • Nitrogen
  • Phosphorus
  • Sulfur
  • Metal ions (e.g. iron)
siderophores s
Siderophores (S)

Receptor

Fe 2+/S

Fe 2+/S

measuring viable bacteria
Measuring viable bacteria

Colony forming units

colony

growth curve
Growth Curve

Stationary

TURBIDITY

(cloudiness)

Autolysis

Log

Lag

TIME

growth curve1
Growth Curve

Stationary

COLONY

FORMING

UNITS

Death

Log

Lag

TIME

generation time
Generation 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
sugar catabolism
SUGAR CATABOLISM
  • Glycolysis
    • Embden Meyerhof Parnas Pathway
    • most bacteria
    • also animals and plants
other pathways for catabolizing sugars
Other pathways for catabolizing sugars
  • Pentose phosphate pathway (hexose monophosphate shunt)
    • generates NADPH
    • common in plants and animals
  • Entner Doudoroff Pathway
    • a few bacterial species
glycolysis
Glycolysis

NAD

NADH

Glucose

Pyruvate

C6

C3

ADP

ATP

fermentation
Fermentation

NADH

NAD

Pyruvate

Short chain alcohols,

fatty acids

(C3)

(C2-C4)

slide23

Krebs Cycle (C4-C6 intermediate compounds)

NAD

NADH

3CO2

Pyruvate

(C3)

(C1)

Oxidative phosphorylation

NADH

NAD

O2

H2O

ADP

ATP

aerobic respiration glycolysis krebs cycle oxidative phosphorylation
Aerobic Respiration =Glycolysis + Krebs Cycle/oxidative phosphorylation
  • Pyruvate to CO2
      • NADtoNADH
      • glycolysis
      • Krebs cycle
  • Oxidative phosphorylation
    • NADHto NAD
    • ADPto ATP
oxidative phosphylation
Oxidative phosphylation
  • converts O2 to H20 (oxidative)
  • converts ADP to ATP (phosphorylation)
  • electron transport chain
  • ubiquinones/cytochrome intermediates
the krebs cycle
The Krebs cycle

X

C

Isocitrate

C2

Acetate

-CO2 NADH

C6

Citrate

+

-CO2

Alpha-keto

glutarate

C4

Oxaloacetate

Pyruvate

-CO2 NADH

x

C

Malate

Succinate

Fumarate

krebs cycle sugar as sole carbon source
Krebs 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

C3

C

C4

krebs cycle fatty acids as sole carbon source
Krebs 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

C6

C4

Malate

C4

the glyoxylate and krebs cycles
The Glyoxylate and Krebs cycles

Isocitrate

Citrate

1

Alpha-keto

glutarate

Glyoxylate

Oxaloacetate

2

+Acetate

Malate

Succinate

Fumarate

Krebs and Glyoxylate cycles

Krebs cycle only

Glyoxylate cycle only

slide30

Krebs Cycle

        • biosynthetic
        • energy storage
  • Removal of intermediates
        • must be replenished
  • Unique enzymatic replenishment pathways
    • sugars
    • fatty acids