growth conditions
DESCRIPTION
growthTRANSCRIPT
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Growth & Culture of Bacteria
Chapter 6
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Binary Division1 to 2 to 4 to 8 to ?
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Phases of GrowthLagAdapt to nutrientsLogActive growthStationaryDeath = Growth rateDeathNutrients consumedpH too low (why?)Optimize curves in production
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Chapter 6
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Chapter 6
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Chapter 6
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Measuring GrowthDirect CountsPetroff-Hauser ChamberPros vs. ConsSerial Dilution10-fold serial dilutionsPros vs. ConsMPN (Most Probable Number)Put 10, 1, and 0.1 ml into 10-mls brothRepeat 5 times per volumeStatistical accurate samplingPublic Health Standards are written for MPN
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Chapter 6
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Chapter 6
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Chapter 6
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Chapter 6
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Measuring Growth-contdTurbiditySpectrophotometerScale%TransmittanceOptical Density or AbsorbanceFiltration0.45 - 0.2 um sizesGrid Pattern on FilterStandards for Public Health0 E.coli / 100 ml of waterAlso used for sterilization
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Chapter 6
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Chapter 6
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Physical Factors: -philespHAcido-, Neutro-, AlkaliphilesCanned foods-Hot Pack vs. Pressure CookingHigh Acids- tomatoesNeutro-corn, beans, meatTemperaturePsychro-, Meso- ThermophilesGrowth CurveProblems
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Chapter 6
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Note the drop-off as you get closer to the Optimum!
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What effect would have a fever have on Mesophiles??
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Temperature ProblemsThermophilesHot tubs-publicHeat Resistant Enzymes in PCRPsychrophilesCold food (growth in transit)Listeria grows in hot dogs
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Salt ConcentrationHalophilesGreat Salt LakeSalt Pork
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Chapter 6
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Physical Factors: contdMoistureBeef JerkyLyophilization (Freeze Dry)OxygenAerboes vs. Anaerobes + ------ + ----------Osmotic PressurePseudomonas grows in distilled waterJelly- Jams (high sugar)Salt Pork (high salt)
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Nutritional FactorsCarbon SourceAuto- or Hetero- CO2 or Organic compoundsNitrogen SourceNO3- ==> NO2 ==> NH3 to Amino Acids ==> ProteinsSulfurPhosphorusTrace ElementsFe, some requiredHost Sideophores bind Fe
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More -trophsAuxotrophsCan live on simple compounds NO3-, GlucoseMake all Amino Acids, Vitamins, etc.PrototrophsRequire complex compoundsVitamins, Amino AcidsFastidiousMost Pathogens
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Types of MediaComplex MediumPeptones, Yeast ExtractFastidiousPrototrophsSynthetic MediumMinimal MediaAuxotrophs
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ExoenzymesSecreted into environmentCatabolize food productsProtease, DNAase, Amylase, LipaseUsed in identification
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Oxygen RequirmentsClassificationAerobicAnaerobicFalcultative AnaerobicMicroaerophilicOutline for TopicMediaCultivationOxygen Toxicity
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Flluid Thioglycollate Medium (FTM)Peptones, Yeast Extracts, Glucose
Thioglycollate-binds O2
Agar-slow diffusion of O2
Rezaruin- O2 indicator
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FTM Media
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Growth ChambersCandle JarsMicroaerophillicGas-PaksAnaerobes & Faculatative Anaerobes
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Chapter 6
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Why Anerobes vs. AerobesO2 is reactive-toxic (binds e-s)Requires 4 e-s to form waterIntermediates are Free RadicalsFree Radicals steal e-sOxidization of compoundsLoss of energy from compoundsDNA molecule breaks
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Chapter 6
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Chapter 6