3. Physiology of Bacteria

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1、Lecture3Content:ReproductionandGrowthpatternsGrowthrequirementBacterialmetabolismCultivationofbacteriaBacterialGrowthBacterialGrowth:istheincreaseinnumberofcells,notcellsizeBacterialreproduction-BinaryFissionGenerationtime:Thetimeittakesforthenumberofbacteriato

2、doubleThegenerationtimeofdifferentkindsofbacteriavariedwidely:Averagetimeinvitro:15-60minsAveragetimeinvivo:5-10hoursGrowthandnutritionIV:BacteriagrowthcurveinliquidLog(logarithmic)phase:Declinephase:thedepletionwhenthebacteriaareadaptofnutritionandthehightothenewc

3、ondition,the10concentrationoftoxinmakenumberwillgrowatanthedeathraterise.Mostcellincrediblerate.9diebutthesurvivormaypersistforalongtime.87654Stationaryphase,becauseoftheLgviableoganisms/ml3exhaustionofnutrientandthe2accumulationoftoxicproduct,thenew-borncellsandthe

4、deathcellsattacha1balance.0Lagphase:bacteriataketimetogetaccustomedtothenew0h4h8h12h16h20h24h28h32h36hlivingcondition.TimeGrowthandnutritionI:Basedontheutilizationofcarboncompounds,bacteriaareclassifiedas:Autotrophs:cansynthesizealltheirorganiccompoundsbyutilizing

5、atmosphericCO&N22.Heterotrophs:unabletosynthesizetheirownmetabolites&dependonpreformedorganiccompounds.Auto=self;hetero=other;troph=feedingEssentialsofBacterialnutritionMacronutrients:neededinlargeramountsNeededinlargequantities:CHONPSCarbon,hydrogen,oxygen,nitr

6、ogen,phosphorous,andsulfur.HandOarecommon.SourcesofC,N,P,andSmustalsobeprovided.Macronutrientsneededinsmalleramounts:+2+3+2+MineralsaltssuchasCa,Fe,Mg,KMicronutrients=traceelements;neededinverytinyamounts;e.g.Zn+2,Mo+2,Mn+28GrowthrequirementI-Physicalrequirement

7、sTemperatureHydrogenionconcentration(pH)OxygenOsmoticpressureGrowthrequirementII-ChemicalrequirementsFactorsAffectingBacterialGrowthPhysicalRequirements-TemperaturePsychrotrophsarecold-tolerantbacteriaorarchaeathathavetheabilitytogrowatlowtemperaturesGrowbetwe

8、en0°Cand20-30°CCausefoodspoilageThermophilsVisibleinhotspringswhensingle-celledphotosyntheticbacteria(cyanobacteria)formdenselayersofbio