微生物学实验报告——细菌的染色观察.pdf

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1、ReportofMicrobiologyExperimentSmears,SimpleStaining,GramStainingandStructuralStainsXXX2012/3/25ShandongUniversityPurpose1.Understandtherationaleandprocedureofallthestainingmethods.2.Performandinterpretallthestains.3.Learntheshapesandstructuresofbacteriainde

2、ep.Background1.SmearPreparationSmearistoplaceathinfilmofbacterialcellsonaslide.Thesmearmustbefixedtokillthebacteria;coagulatedproteinsfromthecellswillcausecellstosticktotheslide.Fixingdenaturesbacterialenzymes,preventingthemfromdigestingcellparts,whichcause

3、thecelltobreak.Fixingalsopreservesmicrobeswithminimalshrinkageordistortionwhenstained.2.SimpleStainStainingproceduresuseonlyonestainarecalledsimplestains.Thedyesareusuallysaltscomposedofchargedcoloredions.Ifthechromophoreisapositiveion,thestainisconsidereda

4、basicstain;ifitisanegativeion,itisanacidicstain.Mostbacteriaarestainedwhenabasicstainpermeatesthecellwallandadheresbyweakionicbondstothebacterialcell,whichisslightlynegativelycharged.3.GramStainGramstainisastainthatclassifiesbacteriaaseithergram-positiveorg

5、ram-negative.Bacteriadifferintheirrateofdecolorization.Thosedecolorizeeasilyarereferredtoasgram-negative,whereasthosethatdecolorizeslowlyandretaintheprimarystainarecalledgram-positive.Thisdifferenceisbecauseofthechemicalandphysicaldifferencesinbacteria’scel

6、lwall.Gram-positivecellwallscontainmultiplelayersofpeptidoglycanswhichgram-negativecellsonlyhaveathinlayer.Whendecolorizedbyalcohol,thecrystalvioletingram-positivecellscannotbewashedoutbecauseofthecompactpeptidoglycan.Sotherewillbedifferentcolorsfordifferen

7、tbacteria.Whenbacteriadie,theircellwallsdegradeandmaynotretaintheprimarystain,givinginaccurateresults.4.StructuralStainsStructuralstainscanbeusedtoidentifyandstudythestructureofbacteriawhenthereisnoelectronmicroscope.Endosporesare“restingbodies”ofseveralgen

8、eraofbacteria.Theydonotmetabolizeandareresistanttoheating,variouschemicals,andmanyharshenvironmentalconditions.Toknowwhetherabacteriumisanendospore-formerandalsothepositionoftheendosporesishelpful.Endo