1 growth and cultivation of bacteria. 2 g rowth requirements oxygen (or absence)oxygen (or absence)...
DESCRIPTION
Oxygen requirementsTRANSCRIPT
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Growth and Cultivation of bacteria
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GGrowthrowth requirements requirements
• oxygen (or absence)oxygen (or absence)• energy energy • nutrientsnutrients• optimal temperatureoptimal temperature• optimal pHoptimal pH
Oxygen requirements
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Obligate aerobesObligate aerobes
• grow in presence of oxygengrow in presence of oxygen• no fermentationno fermentation• oxidative phosphorylationoxidative phosphorylation
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• killed by oxygen • fermentation • no oxidative phosphorylation
• lack certain enzymes:superoxide dismutase O2
-+2H+ => H2O2
catalase H2O2 => H20 + O2
peroxidase H2O2 + NADH + H+ => 2H20 + NAD
Obligate anaerobesObligate anaerobes
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Aerotolerant anaerobesAerotolerant anaerobesnot killed by oxygennot killed by oxygen
• respire anaerobicallyrespire anaerobically
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Facultative anaerobesFacultative anaerobes• fermentation fermentation • aerobic respirationaerobic respiration• survive in oxygensurvive in oxygen
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Microaerophilic bacteriaMicroaerophilic bacteria
• grow grow – low oxygenlow oxygen
• killed killed – high oxygenhigh oxygen
Temperature
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Optimal growth temperature Optimal growth temperature • Mesophiles: Mesophiles:
– human body temperaturehuman body temperature* pathogens pathogens * opportunistsopportunists
• pyschrophilepyschrophile– close to freezing close to freezing
• thermophilethermophile– close to boilingclose to boiling
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pH
• Many grow best at neutral pH
• Some can survive/grow
- acid
- alkali
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Nutrient RequirementsNutrient Requirements• Carbon Carbon • NitrogenNitrogen• PhosphorusPhosphorus• SulfurSulfur• Metal ions (e.g. iron)Metal ions (e.g. iron)
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Siderophores (S)Siderophores (S)
Fe Fe 2+2+//SS
Fe Fe 2+2+//SS
ReceptorReceptorTransport of ironTransport of iron
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Measuring bacterial mass (live + dead) Measuring bacterial mass (live + dead) in liquid culturein liquid culture
TurbidityTurbidity(Cloudiness)(Cloudiness)
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Measuring viable bacteria
colonycolony
Colony forming unitsColony forming units
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Growth Curve
COLONY FORMING UNITS
TIME
Lag
Log
Stationary
Death
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Growth Curve
TURBIDITY(cloudiness)
TIME
Lag
Log
Stationary
Autolysis
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Generation timeGeneration time
• time for bacterial mass to doubletime for bacterial mass to double
• Example Example 100 bacteria present at time 0 100 bacteria present at time 0 If generation time is 2 hrIf generation time is 2 hr After 8 hr mass = 100 x 2After 8 hr mass = 100 x 244
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SUGAR CATABOLISM
• Glycolysis
– Embden Meyerhof Parnas Pathway– most bacteria– also animals and plants
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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
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•
GlycolysisGlycolysisNADNAD NADHNADH
GlucoseGlucose PyruvatePyruvateC6C6 C3C3
ADP ADP ATPATP
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FermentationFermentation
PyruvatePyruvate
(C3)(C3)
NADHNADH NADNAD
Short chain alcoholsShort chain alcohols, , fatty acidsfatty acids(C2-C4)(C2-C4)
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Anaerobic Respiration = Anaerobic Respiration = Glycolysis + FermentationGlycolysis + Fermentation
NADNAD NADHNADH
NADHNADH NADNAD
ATPATP
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Krebs Cycle (C4-C6 intermediate compoundsKrebs Cycle (C4-C6 intermediate compounds)
PyruvatePyruvate 3CO3CO22
(C3)(C3)
NADNAD NADHNADH
NADHNADH NADNAD
Oxidative phosphorylationOxidative phosphorylation
OO22 HH22OO
ADPADP ATPATP
(C1)(C1)
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Aerobic Respiration =Glycolysis +
Krebs Cycle/oxidative phosphorylation
• Pyruvate to COPyruvate to CO22
– NADNAD toto NADHNADH
– glycolysis glycolysis
– Krebs cycleKrebs cycle
• Oxidative phosphorylationOxidative phosphorylation
– NADHNADH to to NAD NAD
– ADPADP to to ATP ATP
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Oxidative phosphorylationOxidative phosphorylation
• converts Oconverts O22 to H to H220 0 (oxidative)(oxidative)
• converts ADP to ATP converts ADP to ATP (phosphorylation)(phosphorylation)
• electron transport chainelectron transport chain
• ubiquinones/cytochrome intermediates ubiquinones/cytochrome intermediates
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The Krebs cycle
Citrate
Isocitrate
Alpha-keto glutarate
Succinate
Fumarate
Malate
OxaloacetatePyruvate
-CO-CO22
Acetate
+-CO-CO2 2 NADHNADH
-CO-CO2 2 NADHNADH
C2
C
C
C4
X
x
C6
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Krebs Cycle - sugar as sole Krebs Cycle - sugar as sole carbon sourcecarbon source
PyruvatePyruvate
AcetateAcetate-CO-CO22
C4C4
PyruvatePyruvate+ CO+ CO22
+Citrate
CCC3C3
Oxaloacetate
Oxaloacetate
-2CO-2CO22
Aspartic acidAspartic acid
Krebs Krebs cyclecycle
ENERGYSTORAGE
BIOSYNTHESISC3C3
CCC2C2
C6C6C4C4
OxaloacetateX
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Krebs Cycle – fatty acids as Krebs Cycle – fatty acids as sole carbon sourcesole carbon source
Fatty acidsFatty acids AcetateAcetate
+ CitrateOxaloacetate
-2CO-2CO22
Aspartic acidAspartic acid
Krebs Krebs cyclecycle
ENERGY
BIOSYNTHESIS
Isocitrate Succinate Glyoxylate+
AcetateAcetate+
MalateMalate
Oxaloacetatex
C4
C2
C2
C4C6
-2CO-2CO22
Krebs cycle
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The Glyoxylate and Krebs cycles
Citrate
Isocitrate
Alpha-keto glutarate
Succinate
Fumarate
Glyoxylate
++ AcetateMalate
Oxaloacetate
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Krebs cycle only Glyoxylate cycle onlyKrebs and Glyoxylate cycles
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Krebs CycleKrebs Cycle
– biosyntheticbiosynthetic
– energy storage energy storage
• Removal of intermediatesRemoval of intermediates
– must be replenishedmust be replenished
• Unique enzymatic replenishment pathwaysUnique enzymatic replenishment pathways
– sugars sugars
– fatty acidsfatty acids
Major nutritional types of procaryotes
Nutritional Type Energy Source Carbon Source Examples
Photoautotrophs Light CO2
Cyanobacteria, some Purple and Green Bacteria
Photoheterotrophs Light Organic compounds Some Purple and Green Bacteria
Chemoautotrophsor Lithotrophs(Lithoautotrophs)
Inorganic compounds, e.g. H2, NH3, NO2, H2S
CO2A few Bacteria and
many Archaea
Chemoheterotrophs or Heterotrophs Organic compounds Organic compounds Most Bacteria,
some Archaea