交大微生物课件growth生长的测定计数

Lecture5-2MicrobialGrowthCHAPTER6BROCKBIOLOGYOFSchoolofLifeScienceandBiotechnologyJiaoTongIII.MeasuringMicrobialShanghaiJiaoTongGrowthHowtocountcellnumbersinaDirectcountofmicrobialTotalcountViablecounttecountingIndirectcountofmicrobialgrowthTurbidimetricShanghaiJiaoTongShanghaiShanghaiJiaoTongDirectmeasurementsofmicrobialgrowth:totalandviablecountsTotalandviablecountingmethodseachhavetheirstrengthsandweaknesses.总菌计数与活菌 ShanghaiJiaoTongShanghaiJiaoTongDirectMeasurements1:TotalcellcountsDirectmicroscopiccount:Thenumberofcellsinapopulationcanbemeasuredbycountingasampleunderthemicroscope.直接显微,Withliquidsamples,specialcountingShanghaiJiaoTongDirectmicroscopiccountingprocedureusingthePetroff-Haussercountingchamber ShanghaiJiaoTongShanghaiJiaoTongShanghaiJiaoTongDeadcellsandlivingcellsareallcountedSmallcellsaredifficulttocountNeedphasecontrastmicroscopeNeedhighcellconcentration,106cells/ml(why?)PrecisionisdifficulttoachieveMotilecellsmustbeimmobilizedbeforecountingShanghaiJiaoTongShanghaiShanghaiJiaoTong DirectMeasurements2:ViableCount活菌记数ShanghaiJiaoTongtetecount/colonycount):Twomethodsofatetecount/colonycount):ShanghaiJiaoTongShanghaiJiaoTongDilutingcellsuspensionsbeforeWiththe temethods,itisimportantthatthenumberofcoloniesdevelo onthe notbetoolarge.Toobtaintheappropriatecolonynumber,thesampletobecountedmustalmostalwaysbeShanghaiJiaoTongDilutingcellsuspensions tewillbemembranefiltrationprocedure.Membranewithdifferentporesizesareusedtotrapdifferentmicroorganisms.IncubationtimesformembranesalsovarywiththemediumandShanghaiJiaoTongLimitationsof tingcounting平 Singlecolonymayarisefrommorethanonecell(cellcfu/mlcolony-formingunit/ml菌落形成单位ToomanyInoculumSuitabilityofIncubationLengthofSizeofShanghaiJiaoTongShanghaiShanghaiJiaoTongMembrane-filteredsamplesgrownonavarietyofmedia.StandardnutrientmediaforatotalbacterialFecalcoliformmediumfordetectingfecalcoliformsthatformbluem-EndoagarfordetectingE.coliandothercoliformsthatproducecolonieswithagreensheen.mol.nghaiShanghaiJiaoTongIndirectMeasurements:Turbidity浊度Principle:acellsuspensionlookscloudy(turbid)totheeyebecausecellsscatterlightpassingthroughthesuspension.Themorecellspresent,themorelightscatteredandhencethemoreturbidthesuspension.ShanghaiJiaoTongShanghaiJiaoTongTurbidityTurbiditymeasurementsofmicrobial(a)MeasurementsofturbidityaremadeinShanghaiJiaoTongLimitationsofturbiditycountingDeadcellsandlivingcellsarenotParticlesinculturedisturbmeasurementNotgoodathighShanghaiJiaoTongContinuousculturethechemostat连续培养:恒化器CanwemaintainapopulationatexponentialgrowthFixedvolumeofcultureGrowthrateandgrowthyieldarecontrolledsimultaneously,notyoucando,FlowsystemofconstantContinuousadditionofmediumandcontinuousremovalofSteadystateGrowthrateandgrowthyieldcanbemanipulatedindependentlyContinuousculture-thechemostatInsuchadevice,thepopulationdensityiscontrolledbytheconcentrationoflimitingnutrientinthereservoir,andthegrowthrateiscontrolledbytheflowrate.BothparameterscanbesetbytheRelationshipbetweennutrientconcentration,growthrate,andgrowthyieldinabatchculture.Atlownutrientconcentrationsbothgrowthrateandgrowthyieldareaffected.ShanghaiJiaoTongGrowthrateandgrowthyieldcanbecontrolledindependentlyinachemostatGrowthratecontrolFlowrateofthefreshmediumintothesystem-dilutionGrowthyieldcontrol(populationdensity)MaintainingapopulationatitsexponentialgrowthphaseforalongtimeShanghaiJiaoTongSteady-staterelationshipsintheThedilutionrateisdeterminedfromtheflowrateandthevolumeoftheculturevessel.稀释率由流速及培养器体积决定.Athighdilutionrates,growthcannotbalancedilutionandthepopulationwashesSteady-staterelationshipsintheAlthoughthepopulationdensityremainsconstantduringsteadystate,thegro