华中农业大学微生物英文版课件

Chapter9MicrobialEcology,Microbialecology=?Environmentalmicrobiology,Thetermmicrobialecologyisnowusedinageneralwaytodescribethepresenceanddistributionsofmicroorganisms.,Microbialecologyisthethestudyofthebehaviorandactivitiesofmicroorganismsintheirnaturalenvironments.,Environmentalmicrobiology,incomparison,relatesprimarilytoall-overmicrobialprocessesthatoccurinasoil,waterorfood,asexamples.Itisnotconcernedwiththeparticularmicroenvironmentwherethemicroorganismsactuallyarefunctioning,butwiththebroader-scaleeffectsofmicrobialpresenceandactivities.,9.1Microorganismsinnatureecosystem,9.2Microbialpopulationinteractions,9.3Biogeochemicalcycles,9.4Plant-microbeinteractions,9.5Bioremediation,Chapter9MicrobialEcology,9.1Microorganismsinnatureecosystem,1.Microorganismsandmicroenvironment2.TerrestrialEnvironments3.FreshwaterEnvironments4.MarineEnvironments,9.1.1Microorganismsandmicroenvironment,populations,guilds,communities,ecosystem,Metabolicallyrelatedpopulationsconstitutegroupingscalledguilds.,Setsofguildsconductingcomplementaryphysiologicalprocessesinteracttoformmicrobialcommunities.,Inamicrobialecosystemindividualcellsgrowtoformpopulations.,Community3,Microbialcommunitiestheninteractwithcommunitiesofmacroorganismstodefinetheentireecosystem.,Thedistributionofmicroorganismsinnatureecosystemdependsontheresources(nutrients)availableandonthegrowthconditions.,Temperature,pH,wateravailability,light,oxygenofahabitatdefinethenicheforeachparticularmicroorganism.,Soilparticlesarenothomogeneousintermsoftheiroxygencontent.Theouterzonesofasmallsoilparticlemaybefullyoxic,whereasthecenter,onlyaveryshortdistanceaway,canremaincompletelyanoxic.,Asoilaggregatecomposedofmineralandorganiccomponents,showingthatlocalizationofsoilmicrobes.Veryfewmicroorganismsarefoundfreeinthesoilsolution;mostofthemoccurasmicrocoloniesattachedtothesoilparticles.,9.1.2.TerrestrialEnvironments,Proportionofdifferentsoilmicroorganismsinsoil,Microbialnumberandbiomassincultivatedfieldsoil（15cm）,Maintypesofsoilmicroorganisms,Therhizosphereisthesoilregioninclosecontactwithplantroots.,Withintherhizosphere,theplantrootsexertadirectinfluenceonthesoilbacteria.Thisinfluenceisknownastherhizosphereeffect.,Intherhizosphere,microbialpopulationsreachmuchhigherdensitiesintherhizospherethaninthefreesoil.,RhizosphereEffect(R/Sratio),(1)removinghydrogensulfide,whichistoxictotheplantroots(2)increasingsolubilizationofmineralnutrientsneededbytheplantforgrowth(3)synthesizingvitamins,aminoacids,auxins,gibberellinsthatstimulateplantgrowth(4)antagonizingpotentialplantpathogensthroughcompetitionandtheproductionofantibiotics,Microbialpopulationsintherhizospheremaybenefittheplantby:,1，neutralism(中性关系)2，commensalism(偏利关系)3，synergism(协同关系)4，mutualism(互惠关系)5，competition(竞争关系)6，antagonism(拮抗关系)7，parasitism(寄生关系)8，predation(捕食关系),9.2Microbialpopulationinteractions,Neutralism,thereisnoanyphysiologicaleffectbetweenthepopulations.,Commensalismisaunidirectionalrelationshipbetweenpopulationsinwhichonepopulationbenefitsandtheotheroneisunaffected.,Synergismindicatesthatbothpopulationsbenefitfromtherelationshipbuttheassociationisnotobligatory.Bothpopulationsarecapableofsurvivingindependently.,MutualismSymbiosisisanobligatoryinterrelationshipbetweentwopopulationsthatbenefitsbothofthem.Lichensiscomposedofafungusandanalga.,Competitionoccurswhentwopopulationsarestrivingforthesameresourceofnutrientsorthehabitat.,Antagonismoccurswhenonepopulationproducesasubstrateinhibitorytoanotherpopulation.,Parasitism,theparasitepopulationisbenefitedandthehostpopulationisharmed.,Predationisawidespreadphenomenonwherethepredatorengulfsorattackstheprey.Thepreycanbelargerorsmallerthantheprey,andthisnormalresultsinthedeathoftheprey.,Classificationofpopulationinteraction,0,Noeffect;+,positiveeffect;-,negativeeffect.,9.3Biogeochemicalcycles,1.Carboncycle2.Nitrogencycle3.Sulfurcycle4.Ironcycle,Carboncycle,Carboncycle,Carbondioxideisincorporated,orfixed,intoorganiccompoundsbysuchphotoautotrophsascyanobacteria,greenplants,algae,andgreenandpurplesulfurbacteria.,Chemoheterotrophsconsumetheorganiccompounds,animalseatphotoautotrophs,especiallygreenplants,andmayinturnbeeatenbyotheranimals.,Whentheorganismsdie,theorganiccompoundsoftheirbodiesaredepositedinthesoilandaredecomposedbymicroorganisms,principallybybacteriaandfungi.Duringthisdecomposition,carbondioxideisreturnedtotheatmosphere.,Nitrogencycle,Proteinsfromdeadcellsandwasteproducts,Microbialdecomposition,Aminoacids,Aminoacids,Ammonia(NH3),ammonification,Almostallthenitrogeninthesoilexistsinorganicmolecules,primarilyinproteins.Whenanorganismdies,theprocessofmicrobialdecompositionresultsinthehydrolyticbreakdownofproteinsintoaminoacids.,Theaminogroupsofaminoacidsareremovedandconvertedintoammonia(NH3).Ammonificationisbroughtaboutbynumerousbacteriaandfungi.,NH4+,N02-,Nitrosomonas,Ammoniumion,Nitriteion,N02-,N03-,Nitriteion,Nitrateion,Nitrobacter,Nitrificationinvolvestheoxidationoftheammoniumiontonitrate,ThegeneraNitrosomonasandNitrobacterareautotrophicnitrifyingbacteria.Theseorganismsobtainenergybyoxidizingammoniaornitrite.Inthefirststage,Nitrosomonasoxidizesammoniumtonitrites.Inthesecondstage,suchorganismsasNitrobacteroxidizenitritestonitrates,Keyprocessesandprokaryotesinthenitrogencycle,Sulfurcycle,Keyprocessesandprokaryotesinthesulfurcycle,9.4Plant-microbeinteractions,1.LichensandMycorrhizas2.Theplantenvironment3.Rootnodulebacteriaandsymbiosiswithlegumes,Lichens,Lichensareleafyorencrustinggrowthsthatarewidespreadinnatureandareoftenfoundgrowingonbarerocks,treetrunks,houseroofs,andsurfacesofbaresoils.Thelichenplantconsistsofasymbiosisoftwoorganisms,afungusandanalga.Lichensconsistofatightassociationofmanyfungalcellswithinwhichthealgalcellsareembedded.,Mycorrhizas,Mycorrhizaliterallymeansrootfungusandreferstothesymbioticassociationthatexistsbetweenplantrootsandfungi.Probablytherootsofthemajorityofterrestrialplantsaremycorrhizal.Therearetwoclassesofmycorrhizae:ectomycorrhizae,inwhichfungalcellsformanextensivesheatharoundtheoutsideoftherootwithonlylittlepenetrationintotheroottissueitself,andendomycorrhizae,inwhichthefungalmyceliumisembeddedwithintheroottissue.,Mycorrhizas,TypeofMycorrhizas:EctomycorrhizaandEndomycorrhizaMorphologyandFunctionofMycorrhizalInfectionMycorrhizaandPlantNutritionApplicationPotentialofVAMinAgriculturalpracticeandEcosystemDevelopmentandApplicationofMolecularProbesConstructionandAnalysisofGenomicLibrary,Mycorrhizas,EctomycorrhizasEndomycorrhizasEctendomycorrhizas,Functionsofmycorrhiza,RootNoduleBacteriaandSymbiosiswithLegumes,StagesinNoduleFormationBiochemistryofNitrogenFixationinNodulesGeneticsofNoduleFormation:nodGenesGeneticCooperativityintheRhizobium-legumeSymbiosisConstructionandApplicationofGenetic-engineeredRhizobium,SymbiosisofFrankiaandNon-leguminousPlant,MorphologyandPhysiologicalCharacteristicofFrankiaHostsApplicationPotential,8.5Bioremediation,1.Pollutants2.Meansofbioremediation,Pollutants,1,Microorganismsareanimportantpartofecosystems2,Microbialcommunitiesarecomplex3,Microbialgrowthrequiresnutrientsandallofwhichmustbepresentinusableforms4,Mostmicroorganismsnormallyassociatedwithhigherorganismsandthosegrowninthelab.tendtobelessabletocompeteandsurviveinsoilsandwaters5,Extremeenvironmentsrestricttherangeofmicrobialtypeswhichareabletosurviveandfunction,Concepts,MicroorganismsinNature,DistributionofmicroorganismsIn:SoilWaterAirF