实验三-七 大分子物质的水解实验和IMVIC实验.ppt

《实验三-七 大分子物质的水解实验和IMVIC实验.ppt》由会员上传分享，免费在线阅读，更多相关内容在PPT专区-天天文库。

1、实验三－七大分子物质的水解实验和IMVIC实验一、教学要求了解微生物一些生化反应的原理及其在微生物鉴定中的应用。二、简介Toidentifybacteria,wemustrelyheavilyonbiochemicaltesting.Thetypesofbiochemicalreactionseachorganismundergoesactasa"thumbprint"foritsidentification.Thisisbasedonthefollowingchainoflogic:Eachdifferentspecie

2、sofbacteriumhasadifferentmoleculeofDNA(i.e.,DNAwithauniqueseriesofnucleotidebases).SinceDNAcodesforproteinsynthesis,thendifferentspeciesofbacteriamust,bywayoftheiruniqueDNA,beabletosynthesizedifferentproteinenzymes.Enzymescatalyzeallthevariouschemicalreactionsofwh

3、ichtheorganismiscapable.Thisinturnmeansthatdifferentspeciesofbacteriamustcarryoutdifferentanduniquesetsofbiochemicalreactions.Whenidentifyingasuspectedorganism,youinoculateaseriesofdifferentialmediaAfterincubation,youthenobserveeachmediumtoseeifspecificendproducts

4、ofmetabolismarepresent.Thiscanbedonebyaddingindicatorstothemediumthatreactspecificallywiththeendproductbeingtested,givingsomeformofvisiblereactionsuchasacolorchange.Theresultsofthesetestsonthesuspectedmicroorganismarethencomparedtoknownresultsforthatorganismtoconf

5、irmitsidentification.1、MacromoleculeshydrolysisExoenzymesdiastase（amylase）、protease、lipaseendoenzymesStarchhydrolysisSomebacteriaarecapableofusingstarchasasourceofcarbohydratebutinordertodothis,theymustfirsthydrolyzeorbreakdownthestarchsoitmayenterthecell.Thebacte

6、riumsecretesanexoenzymewhichhydrolyzesthestarchbybreakingthebondsbetweentheglucosemolecules.Thisenzymeiscalledadiastase（amylase）.StarchhydrolysisproteinhydrolysisProteinsaremadeupofvariousaminoacidslinkedtogetherinlongchainsbymeansofpeptidebonds.Manybacteriacanhyd

7、rolyzeavarietyofproteinsintopeptides(shortchainsofaminoacids)andeventuallyintoindividualaminoacids.Theycanthenusetheseaminoacidstosynthesizetheirownproteinsandothercellularmoleculesortoobtainenergy.Thehydrolysisofproteinistermedproteolysisandtheenzymeinvolvediscal

8、ledaprotease.proteinhydrolysis2、fermentationofcarbohydratesFacultativeanaerobicandanaerobicbacteriaarecapableoffermentation,ananaerobicprocessduringwhic