Section IFundaments of MicrobiologyThe Growth, Survival, & Deathof MicroorganismsSHIHEZI UNIVERSITY
Section I Fundaments of Microbiology The Growth, Survival, & Death of Microorganisms SHIHEZI UNIVERSITY
KEY TERMSBiocideExponential growthGrowth CurveBacteriostaticBinary fissionBactericidalSterilizationDisinfectantSepticAntisepticAsepticAntibioticSHIHEZI UNIVERSITY
KEY TERMS Exponential growth Growth Curve Binary fission Biocide Bacteriostatic Bactericidal Sterilization Disinfectant Septic Antiseptic Aseptic Antibiotic SHIHEZI UNIVERSITY
Survival of Microorganisms in theNatural EnvironmentPopulation of microorganisms in thebiosphere is roughly constantGrowth is counterbalanced by death The survival of microbial within its niche isdetermined by successful competition fornutrientsSHIHEZI UNIVERSITY
Survival of Microorganisms in the Natural Environment Population of microorganisms in the biosphere is roughly constant Growth is counterbalanced by death The survival of microbial within its niche is determined by successful competition for nutrients SHIHEZI UNIVERSITY
Survival of Microorganisms in theNatural Environment Most of our understanding of microbialphysiology has come from the study of isolatedcell lines growing under optimal conditionsMany microorganisms compete in the naturalenvironment while under nutritional stress, aphysiologic state quite unlike that observed in theiaboratory A vacant microbial niche in the environment willsoon be filled Public health procedures that eliminate pathogenicmicroorganisms by clearing their niche are likely to beess successful than methods that leave the nicheoccupied by successful nonpathogenic competitorsSHIHEZIUNIVERSITY
Survival of Microorganisms in the Natural Environment Most of our understanding of microbial physiology has come from the study of isolated cell lines growing under optimal conditions Many microorganisms compete in the natural environment while under nutritional stress, a physiologic state quite unlike that observed in the laboratory A vacant microbial niche in the environment will soon be filled Public health procedures that eliminate pathogenic microorganisms by clearing their niche are likely to be less successful than methods that leave the niche occupied by successful nonpathogenic competitors. SHIHEZI UNIVERSITY
The Meaning of GrowthGrowth is the orderly increase in the sumof all the components of an organismIncrease in size that results when a cell takesup water or deposits lipid or polysaccharide isnot true growthCell multiplication is a consequence ofgrowthIn unicellular organisms, growth leads to anincrease in the number of individualsSHIHEZI UNIVERSITY
The Meaning of Growth Growth is the orderly increase in the sum of all the components of an organism Increase in size that results when a cell takes up water or deposits lipid or polysaccharide is not true growth Cell multiplication is a consequence of growth In unicellular organisms, growth leads to an increase in the number of individuals SHIHEZI UNIVERSITY
The Measurement of MicrobialConcentrations Cell ConcentrationTurbidity of a culture, measured by photoelectricmeansThe viable cell count is usually considered themeasure of cell concentrationBiomass Density+ determining the dry weight of a microbial cultureafter it has been washed with distilled waterIn practice, the investigator customarily preparesastandard curve that correlates dry weight withturbiditySHIHEZI UNIVERSITY
The Measurement of Microbial Concentrations Cell Concentration Turbidity of a culture, measured by photoelectric means The viable cell count is usually considered the measure of cell concentration Biomass Density determining the dry weight of a microbial culture after it has been washed with distilled water In practice, the investigator customarily prepares a standard curve that correlates dry weight with turbidity SHIHEZI UNIVERSITY
Measuring bacterial masss (live +dead) in ligquid cultureTurbidity(Cloudiness)SHIHEZI UNIVERSITY
Measuring bacterial mass (live + dead) in liquid culture Turbidity Turbidity (Cloudiness) (Cloudiness) SHIHEZI UNIVERSITY
Measuring viable bacteriaColony forming unitscolonySHIHEZI UNIVERSITY
Measuring viable bacteria colony colony Colony forming units Colony forming units SHIHEZI UNIVERSITY
Bacteria MultiplicationCell all-Plasma membraneChromosomeBinary fission2insocia苗刻SHIHEZI UNIVERSITY
Bacteria Multiplication Binary fission G- 菌分 分 裂 SHIHEZI UNIVERSITY
The Growth CurveTable4-2. Phasesof microbial growth curveoieSectionofPhaseCurveGrowthRateZeroALagBBAccelerationIncreasingCExponentialConstantDRetardationDecreasingLLMaximum stationaryZeroTimeLLDeclineNegative death)Figure 4-2. Cell oncentration curve.A: The Lag PhaseE: The Maximum Stationary PhaseC: The Exponential PhaseF: The Death Phase (Decline PhaseSHIHEZI UNIVERSITY
The Growth Curve A: The Lag Phase E: The Maximum Stationary Phase C: The Exponential Phase F: The Death Phase (Decline Phase) SHIHEZI UNIVERSITY