microbial metabolismfaculty.collin.edu/mweis/microbiology/lecture/adobe... · 2005-09-23 ·...

Microbial Metabolism

Biochemical diversity

Metabolism

DefineRequirements

EnergyEnzymes

RateLimiting stepReaction time

TypesAnabolic

EndergonicDehydration

CatabolicExergonicHydrolytic

Metabolism Relationships

Metabolic Diversity

Energy generating metabolismFermentation

AlcoholAcid Formation

Lactic AcidMixed AcidsOthers

RespirationAerobicAnaerobic

Biosynthesis of secondary metabolitesHeterotrophicAutotrophic

Energy

FormsKineticPotential

UseChemicalMechanicalElectricalRadiation [EM]

Chemical TypesATPUTPGTP

Heat Byproduct45%

Various Types of Prokaryotic Energy Production Processes

FermentationAnaerobic RespirationAerobic RespirationLithotrophyPhotohetertrophyAnoxygenic photosynthesisMethanogenesis

Enzymes

StructureProteinRibozyme [ribosome]

Characteristic functions

Active siteSpecificModified Forms

InactiveActive

Coenzyme/Cofactor-ase

Polymerase

Others: Lyases, Hydrolases,Isomerases, Transferases

Enzyme Characteristics

Enzyme StructureApoenzyme

ProteinAllosteric site

CofactorMetal ions

CuZnMgFeCa

CoenzymeVitaminsCoANADFADFMN

Create Holoenzyme with active site

Allosteric site

Factors Affecting Enzymes

TemperaturepHAcids/basesUV lightConcentration of substrates

Enzyme Inhibition

Noncompetitive atAllosteric siteCompetitive

at active siteExcitatoryInhibitoryReversible

Irreversible

Glycolysis: Embden-Meyerhoff

GlycolyticCytoplasmAnaerobicEnd products

2 Pyruvic acids4-2 = 2 net ATP2 NADH2 H20

Lactic Acid Formation

Glycolysis: PPP

Breakdown 5-6 CCytoplasmAnaerobicEnd products

ATPNADPHCO24,5,6,7 C

AANucleotidesGlycolytic pathwaysPhotosynthesis

Glycolysis: Entner-Duodoroff [E-D]

GlycolyticCytoplasmAnaerobicDifferent enzymes

PseudomonasEnterococcus

End products2-1 = 1 net ATPNADPHNADH2 Pyruvic acids2H20

Glycolytic Pathways used by various Bacteria

Bacterium E-M PPP E-D

Acetobacter aceti - + -

Bacillus subtilis major minor -

E. coli + - -

Lactobacillus acidophilus

+ - -

Pseudomonas aeruginosa

- - +

Vibrio cholera minor - major

Anaerobic Processes

Lactic AcidLactobacillus

Mixed AcidEnterobacteriaceae

ButanediolKlebsiellaEnterobacter

Butyric AcidClostridia

Butanol-AcetoneClostridia

Propionic AcidCorynebacteria

Fermentation

Fermentation Pathways

Fermentation Summary

AnaerobicCytoplasmPartial OxidationSmall amounts of ATP generated via substrate level phosphorylationOrganic intermediaries as final electron acceptorsEnd products

Acid: Lactic Acid, Acetic Acid, Butryic Acid, AcetoneAlcohol: Ethanol, IsopropylGas : CO2, H2Contaminants

Summary

Carbohydrate Fermentation Tests

Phosphorylation

Substrate LevelDirect transfer of phosphateGlycolysis

Oxidative PhosphorylationElectron transferChemiosmosis

PhotophosphorylationLight energy to chemical energy

Substrate Level Phosphorylation

Aerobic Respiration

Mitochondria of Eukaryotes

Plasma [cell] membrane

Acetyl CoA Formation

Acetyl CoA Final Structure

Krebs Cycle

Oxidation in Krebs Cycle

Dehydrogenation

Use of hydrogen in oxidative reactions

Removal of electron from hydrogenCarried on vitamin B derivatives

Energy released is trapped in chemical bonds

Redox Reactions

Oxidation

Reduction

Catabolism + Anabolism

Eukaryotic ETC

Prokaryotic ETC

Vit B based FlavoproteinsIron based CytochromesCoEnzyme Q

ETC Steps

Electrons from NADH or FADH2 to flavoproteinsH+ pumped into periplasmElectrons transported

To Iron-Sulfur proteins from NADHTo CoQ from FADH2

CytochromesFinal Electron Acceptor

O2 if AerobicOther if Anaerobic

Proton Pump

ETC: NAD

ETC: Cytochromes

Cytochrome Oxidase

Oxidase Test

ATP Synthetase

Anaerobic Respiration

Use of another compound than O2 as final electron acceptor in the ETCExamples

Nitrate ion NO3-[Pseudomonas, E coli, Bacillus]

NO2-N2ON2

Sulfate ion SO4= to H2S

MethanogensCarbonate ion CO3= to CH4

Methanogens

Nitrogen Reduction Test

Nitrate Reduction+ with Zinc Nitrate Reduction

Neg with zincNitrate Reduction +

Other Catabolic Processes

ProteinDeaminationDecarboxylationDehydrogenation

LipidGlycerolFA

Beta oxidationAcetyl CoA

Biosynthesis

PolysaccharideKeto acidsAAGlycerol from FA

LipidGlycerol + FA

AAKeto acids + NH2

NucleotidesNitrogen bases from Keto acids + NH25 C sugars from alternate CH20 Metabolism

FunctionsPolysaccharide

Cell wall componentsLipid

Cell wallPlasma membranes

AA/ProteinCell wall / membrane componentsEnzymesToxins

NucleotideDNARNAATPNADNADP

Protein Synthesis and Enzyme Regulation

MetabolismSummary

Questions?