李友国环境宏基因组

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1、近代生物学研究技术李友国华中农业大学生命科学技术学院背景简介宏基因组的概念宏基因组文库的构建a．环境HMWDNA制备b．载体选择c．宿主细菌宏基因组文库的筛选应用实例分析发展趋势第五讲环境宏基因组技术的研究和应用（3学时）EnvironmentalMetagenomics：ResearchandApplication第六讲稳定性同位素探针技术-微生物个体和功能偶联（1学时）StableIsotopeProbing-LinkingMicrobialIdentitytoFunction背景简介基本原理应

2、用实例分析IntroductionDefinition:whatisenvironmentalmetagenomics?ConstructionofMetagenomicLibrariesApproachestoMetagenomicAnalysisApplicationofMetagenomicsFutureDirectionsOutline1.ModernMicrobiology—aPureCultureIsNotEnough2.rRNAAnalysisandCulturingIntroduct

3、ionThe“GreatPlateCountAnomaly”•Directmicroscopiccountsofnaturalsamplesrevealfarmoreorganismsthanarerecoverableoncultureplates•Why?1.Directcountsmayincludelivecellsaswellasdeadcells(thatdonotgrowonaplate)2.Wecan’tcultureonaplatealltheorganismsinhabiting

4、agivensample•Example:Thecaseofthe“unculturable”ArchaeaCulturebias-WhatdoweseeNumberofbacteriawesawinthemicroscopeusuallyexceedsthenumberofbacteriawecangrowinthelabTotalbacterialcountwas4.2x1010cellsgram-1Totalcolonyformingunitswere4.2x106cfugram-14.2x1

5、06x100=0.01%wereculturable4.2x1010WHOTHEYARE?andWHATTHEYAREDOING?rRNAapproach(16S/18SrRNAgene)FunctionalgenesapproachMicrobialecologytrytofindtheansweronthequestions:TheProblemoftheUnculturedThegreatmajority(upto99%)ofbacteria,inmanyenvironments,haveno

6、tbeencultured.Thediversityofthis“wealth”hasbeenrevealedby16SrDNAsequenceanalysis.However,whatdothese“unknowns”actuallydo?“Traditional”MolecularApproachesAmplifysequencesfrom“environmentalsamples”“A”rRNAsequencesanalysis-fortaxonomy“B”individualstructur

7、algenesCulturing16STreeBut,thisdoesnottelluswhattheyDO.Environmentalmetagenomics(SchlossandHandelsman,2003)Definition:Theculture-independentgenomicanalysisofmicrobialcommunitiesorthecompoundgenomeoftheenvironmentalmicrobiota.Metagenomics-thekeytotheunc

8、ulturedmicrobesMetagenomicsdescribesthefunctionalandsequence-basedanalysisofthecollectivemicrobialgenomesinanygivenenvironmentalsample.JoHandelsmanMetagenomics1.Metagenome(environmentalgenome)-thegenomesofthetotalmicrobiotafoundinnature