PowerPoint PresentationCase presentationSlide 3Slide 4Slide 5To the Micro LabSlide 7Bacterial growthMacronutrientsMicronutrientsVitamins: Growth FactorsNutrientsAtmospheric conditionsBacterial growth phasesSlide 15Bacterial metabolismMetabolic classes of bacteriaSame word - slightly different meaningsMetabolic energyAerobic respirationSlide 21Production of EnergyGlycolytic pathwayGlycolytic pathway- Preparative (investment) phaseGlycolytic pathway- Payoff phaseSlide 26Krebs cycle - overviewInitial step - Krebs cycleKrebs cycle- detailedKrebs cycleElectron Transport + Oxidative PhosphorylationElectron TransportSlide 33Overview- Metabolic PathwaysSlide 35Anaerobic respirationSlide 37FermentationSlide 39Slide 40Slide 41PhotosynthesisSummary: Aerobic RespirationSummary: Anaerobic RespirationSummary: FermentationUniversal features Bacterial energy productionSlide 47Slide 48Back to our patientSlide 50The point is….Bacterial Growth and MetabolismCharles BerensonDepartment of MedicineInfectious Diseases [email protected] presentation54 y/o man with T- 101.5.c/o malaise for 2 monthsOccasional chillsT- 101.5Cardiac exam - Grade 3/6 systolic murmur in mitral valve regionLesions on fingers, toes and conjunctivaeCase presentationSplinter hemorrhagesIndicative of septic emboliCase presentationJaneway lesionsIndicative of septic emboliCase presentationPresumptive diagnosisInfective endocarditisProblem:Need to identify the pathogen to treat effectivelyIn endocarditis - invariably have a bacteremiaMultiple sets of blood cultures grow the pathogenTo the Micro LabBlood cultures grew out bacteria within 24 hrs:Gram stain of contents of blood culture bottle:Lab tech plated out material onto a blood agar platePut it in the incubatorTo the Micro LabNext morning, pulled out the blood agar plateExpected FoundNothing was growing!!!How come?Answer: The causative bacterium has special growth and metabolic requirementsBacterial growthBacterial growth - binary fissionMost bacteria grow in artificial culture mediaNotable exceptions:Some - only on selective media - LegionellaSome-obligate intracellular pathogens- ChlamydiaRequire tissue or cellsSome- require animal models - Mycobacterium lepraeSome- have never been grown - Treponema pallidumMacronutrientsFeSulfurK+Ca +2Mg+2Elements required in large amounts by bacteria to growAnd an energy sourceN2H2CO2CarbonPO4MicronutrientsElements required in trace amountsMn+2Zn+2CobaltMolybdenumNickelCu+2SeleniumVitamins: Growth FactorsP-aminobenzoic acid - precursor of folic acidFolic acid- carbon metabolismBiotin- fatty acid biosynthesisCobalamin (B12) - reduction of single carbonsNicotinic acid (niacin) - precursor of NAD+Riboflavin - Precursor of FMNThiamine (B1) - decarboxylationsPyridoxal group (B6) - amino acid formationNutrientsPrototrophA microorganism that can derive all nutritional requirements for growth from the micronutrients and macronutrients supplied.FastidiousMicroorganisms that have complex and special nutrient requirementsMight require special vitamins or amino acids to growAtmospheric conditionsCO2 - may be required as a supplementOxygenObligate aerobe - absolute requirement for O2Microaerophilic- optimal growth at low O2 pressureFacultative aerobe (facultative anaerobe) - grow either aerobically or anaerobicallyObligate anaerobe - ideal growth in absence of O2Bacterial growth phasesBacteria grow in four phasesBacteria have different requirements in eachLag phase - initial, beginning of growthLogarithmic (or exponential) phaseGreat increase in numbersStationary phaseNo increase in number of bacteriaDeathDecline in bacterial numbersBacterial growth phasesBacterial metabolismBacterial cells are highly specialized energy transformersMetabolism refers to all the biochemical reactions in a cellGenerated by oxidation reactions of substratesADP--->ATP Stores energy for the cellStore energy in thio-ester bonds tooEnergy--->Synthesize organic compounds needed by the cellMetabolic classes of bacteriaHeterotrophicEssentially all pathogenic bacteriaObtain energy from organic compoundsPhotosyntheticSynthesize their own glucoseAutotrophicNo sunlightNo organic compoundsUse inorganic compounds - e.g. minerals; CO2Less apt to be pathogenicSame word - slightly different meaningsAerobic growth refers to need for oxygen for growthAerobic respiration refers to oxygen acting as the final electron acceptor for metabolism“Cause you know sometimes words have two meanings.”Jimmy Page, Robert PlantMetabolic energyBacteria may generate energy by:Aerobic respiration- Final electron acceptor ----> OxygenAnaerobic respirationFermentationPhotosynthesisAerobic respirationMajor energy-producing mechanism for aerobesProvides ATP + metabolic intermediatesThree major pathways - linked to one anotherGlycolysis or Glycolytic pathway (Embden-Meyerhof)Krebs cycle (Citric Acid Cycle)Electron transport chain-oxidative phosphorylationAerobic respirationFor all three pathways:Glucose = most common substrateThe major energy sourceBacteria oxidize glucoseC6H12O6 + 6O2 -----> 6CO2 + 6H2O + energy1 molecule glucose ----> up to 38 molecules of ATPProduction of EnergyGlycolytic pathwayGlucose is the primary substratePyruvate is the primary end-productGlycolytic pathway-Preparative (investment) phase2 ATP’s are ‘spent’Glycolytic pathway-Payoff phase4 ATP’s + 2 NADH’s are gainedGlycolytic pathway1 glucose ----> 2 pyruvatesNet gain of +2 ATP’sAnd NADH generatedConverted into more ATP1 NADH can convert into ~3 ATP’s --- later on.Krebs cycle - overviewGlucose+Initial stepInitial step - Krebs cycleGenerates 2 NADH = EnergyKrebs cycle- detailedKrebs cycle1 glucose ----> 2 pyruvatesRespiratory process - uses O2Initial step - Pyruvate - is decarboxylated to CO2 and acetyl coenzyme A2 NADH’sLater portion - cycleNet gain of +2 ATP’sAnd 6 more NADHAnd 2 FADH2Converted into more ATP ---- later on.Electron Transport + Oxidative PhosphorylationSeries of electron transfers within the cytoplasmic membraneGenerate ADP and ATPEach NADH = 3 ATP’sEach FADH2 = 2 ATP’sAccomplished with cytochromes and enzymesElectron