微生物生态学课件

Microbiologyandplantinteractionsresistenceonheavy-metal\nHeavymetalsbeingtransferredtohumansviathefoodchainwouldfinallythreatenhumanbeingshealth.Heavy–metalpollutants\n\nBioremediationonheavymetals\nMetalresistanceofmicroorganismsPlantrhizospherebacteriaPlantendophyticbacteria\nGrowinplantrootsystem.Withbacteria,actinomycetes,fungi,algae,andtheprotozoa.Alternaterelationshipbetweenthemandplant.Plantrootsinteractionandpromoteeachother.Rhizospherebacteria\nBacteriaWidelydistributed,manyvarieties,fastmetabolismandreproduction.Chemicalcompositionofbacterialcellwallscontainmanyheavymetalionsadsorptiongroups,suchascarboxyl,amino,hydroxyl.\n\nCyanobacteria\nFungiSmallmold,single-celledyeastandfruitingbodyoflarge-scalefungus.Theircellwallscontainconsistslargelyofchitinandglucan.Fungihavepotentialforheavymetaladsorptionability.\nSaccharomycesCerevisiaeWhite-rotfungiadsorbePb2+,thehighestremovalratecanreach95%.BlackrhizopusadsorbeAg+,Pb2,Li+andCd2+,Zn2+andNi2+,Cu2+,suchasheavymetalions.\nAlageWidedistribution,agoodbiologicaladsorbent.Thewallsofalgaehasalargersurfacearea.Cellwallshaveacertainchargeandviscous,thesecharacteristicsmakethemetalionhastheability.\nScenedesmusObliquusHasalargeradsorptioncapacitytoUO22+.TheUO22+concentrationinthewaterfrom5.0mg/Lfellto0.05mg/L.\nAkindofparasiticbacteriainplantbody,allplantshaveendophytes.Endophyticbacteria(PGPB)isakindofparasiticlife,promotethegrowthofthehost.Canenhanceplantresistancetopathogens,drought,heavymetal.Endophyticbacteria\nFromElsholtziasplendensandduckplantargrass(Commelinacommunis).\nFirmicutes,Actinobacteria,Proteobacteria.Thesebacteriastrainsincopperresistanceofmaingroups.\nTheCr6+resistantplantgrowthpromotingbacteria(PGPB),Pseudomonassp.PsA4andBacillussp.Ba32wereisolatedfromheavymetalcontaminatedsoilsandtheirplantgrowthpromotingactivityontheIndianmustard.\nReleaseofchelatingagentandironcarrier.Acidificationofthesoilenvironment,ChangetheREDOXpotential.Reducetheabsorption.IncreasethedischargeOxidationreductionModeofresistancetoheavy-metal\nMechanismsofresistencetoheavy-metal\nReducetheabsorptiontheheavymetalcontentinthemicrobialcellsatalowlevelismaintainedwithoutcausingtoxiceffectsoncells.AsatypeofstaphresistanceofCd2+isthecase.\nIncreasethedischargesomemicroorganismsmaybeproactivemannerbyheavymetalionswithinthecellisdischargedoutsidethecell,thusmaintaininglowlevelsofthecell.AsonekindofresistancetoBacilluscopper.\nOxidationreductionmanymicrobialoxidationorbyreduction(inmostcases)fromthehightoxicityoftheheavymetaltransformedintolesstoxicvalencevalencestate,therebyliftingtheheavymetaltoxicity.Forexample,theresistanceofmercurythatisthecase.\nBondedtotheoutercellsReducingtheconcentrationoftoxicheavymetalsintheenvironment,thepurposeofdetoxification.Escherichiacolicopperresistanceeffectasthatisso,itcanbesecretedproteinscapableofbindingtocopperions,therebyreducingtheeffectiveconcentrationofcopperions.\nAdsorptionManymicrobialcellsurfacehasaspecialstructure,canabsorbheavymetalionsandthustoreducetheconcentrationofheavymetalionsinsolution.\nCurrentresearchprogressMustard(Brassicajuncea)andCr-resistantstrains.Cr-resistantstrainsplantappliedtoMustardIncreasebiomessresault\nCr-resistantstrainsPseudomonassp.PsA4andBacillussp.Ba32appliedtomustard(Brassicajuncea).TheresultsshowedthatvaccinatedPsA4mustardorBa32haveincreasedin95.3mg/gand198.3mg/gCr(6+)biomassinthesoil.\nCastor(Ricinuscommunis)andnickel,zincresistancestrains.isolateelecteinoculateincrease\nisolatedfromtherhizospheresoilmicrobes,afternickel,zincresistancescreening.electedtheheavymetalresistantstrainsPseudomonassp.AndPseudomonasjessenii.inoculatedthemtocastor(Ricinuscommunis),theyfoundasignificantincreasecastorbiomass,andincreasedtheaccumulationofZn,Ni,Cu's.\nProspectsHeavymetalcontaminationofsoilgrowingprobleminmanyoptionsinphytoremediationhasitsuniqueadvantages,thefocusoftheproblemishowtoincreasetheresistanceofplantstoheavymetals.\nAsanewway,biologicalcontrolhashugepotential,butisstillinitsinfancy.Withfurtherresearch,itisexpectedtofindmoremicrobialresources,anddevelopingnewtechnologiestomakepracticalapplicationspossible.\n