简介:TheimpactofpHchangesonmicrobialbiomasscarbon(Cmic)andmicrobialbiomassphosphorus(Pmic)wereexaminedfor3redsoilsundercitrusproductionwithdifferentlengthsofcultivation.SoilpHsignificantlyaffectedCmicandPmic.TheCmicandPmicchanges,asafunctionofsoilpH,appearedtofollowanormaldistributionwiththeoriginalsoilpHvalueattheapexandaspHincreasedordecreasedcomparedtotheoriginalsoilpH,CmicandPmicdeclined.Moreover,therewerecriticalpHvaluesatbothextremes(3.0ontheacidicsideand8.0to8.5onthealkalineside),beyondwhichmostofmicroorganismscouldneversurvive.TheeffectofpHonCmicandPmicwasalsorelatedtotheoriginalsoilpH.ThehighertheoriginalsoilpHwas,thelessCmicorPmicwereaffectedbypHchange.ItissuggestedthatsoilmicroorganismsthatgrowinasoilenvironmentwithamoreneutralsoilpHrange(I.e.pH5.5-7.5)mayhaveagreatertolerancetopHchangesthanthosegrowinginmoreacidicormorealkalinesoilpHconditions.
简介:Astrainofyeast,whichcanendurehighosmoticpressure,isemployedforthesensitivematerialofthemicrobialBODsensor.Twoimmobilizationmethodsareused,I.e.CalciumalginategelbeadsandPVAgelbeads.TheresultsshowthatthePVAgelbeadsisbetter.TheinfluencesofosmosisandheavymetalionsontheyeastentrappedinthePVAgelbeadsarealsostudiedintheexperiment.
简介:Anincubationstudywasperformedtoelucidateexogenousrareearthelements(RE)influencingonmicrobialbiomass,microbialecophysiologicalparameterscmic/corg,metabolicquotientqCO2andrespiratoryrateinrelationtotemporalavailabilityinpaddysoil.Sixsampleswereaddeddifferentconcentrationsbetween0and2000mg*kg-1REEsinsoil.ResultsshowthatexogenousREhaveslightstimulativeeffectsonmicrobialindicesinpaddysoilatlowconcentrationintheearlystageafteraddingRE,whilehavinginhibitoryeffectsathighconcentration.TheinhibitionisstrengthenedwithincreasingREconcentrationandisweakenedwithincreasingincubationtime.PrincipalcomponentanalysisoftheBIOLOGdataindicatesthatmicrobialcommunitystructureshavechanged,carbonsourcesconsumptionofmicroorganismsinpaddysoilbecomesmuchmorerapidafter8weeks,andunderREstress,thechangeofmicrobialcommunitystructuresisalong-termeffect.
简介:Thisstudywasdesignedtounderstandtheimpactofmethylbromide(MB)(CH3Br)anditsalternativesonbothfree-livingandroot-knotnematodesinthesoil.Arandomizedcompleteblockexperimentwithsixtreatmentsand4replicates(eachreplicateinaseparategreenhouse)wasestablishedinQingzhou,ShandongProvince,China.InadditiontoMBanduntreatedcontrol(CK)treatmentstherewerefouralternativesoilfumigationpracticesincludingMB+virtuallyimpermeablefilms(VIF),metamsodium(MS),MS+VIFandsoilsolarizationcombinedwithselectedbiologicalcontrolagents(SS+BCA).Twotomato(LycopersicumesculentumMill.)cultivars,cv.Maofen-802fromtheXianInstituteofVegetableScience,China,andcv.AF179BrillantefromtheIsraeliHazeraQualitySeeds,wereselectedastestcrops.TheresultsindicatedthatRhabditidaewasthemostdominantpopulationwithpercentageabundanceashighas85%ofthetotalnumberofidentifiedfree-livingnematodes,followedbythatofCephalobidae.Methylbromideanditsalternativesexceptforthenon-chemicalSS+BCAtreatmentcontrolledthetargetpest,root-knotnematodes.Also,theimpactofthethreechemicalalternativesonfree-livingnematodenumberandfunctionalgroupabundancewassimilartotheimpactassociatedwithatypicalmethylbromideapplication.Chemicalfumigationpractices,especiallythatwithMB,significantlyreducedthenumberofnematodesinthesoilandsimultaneouslysignificantlyreducedthenumberofnematodegeneratherebyreducingnematodediversity.Allthefoursoilchemicalfumigationactivitiesdecreasedsoilmicrobialbiomassandhadanobviousinitialimpactonmicroorganismbiomass.Furthermore,bothplant-parasiticandfungivorenematodeswerepositivelycorrelatedwithsoilmicrobialbiomass.
简介:Theculturablebacterialpopulationandphospholipidfattyacid(PLFA)profileofcasingsoilwereinvestigatedatdifferentmushroom(Agaricusbisporus)croppingstages.ThechangeinsoilbacterialPLFAswasalwaysaccompaniedbyachangeinthesoilculturablebacterialpopulationinthefirstflush.ComparativelyhigherculturablebacterialpopulationandbacterialPLFAswerefoundinthecasingsoilattheprimordiaformationstageofthefirstflush.TherewasasignificantincreaseintheratiooffungaltobacterialPLFAsduringmushroomgrowth.MultivariateanalysisofPLFAdatademonstratedthatthemushroomcroppingstagecouldconsiderablyaffectthemicrobialcommunitystructureofthecasingsoil.Thebacterialpopulationincreasedsignificantlyfromcasingsoilapplicationtotheprimordiaformationstageofthefirstflush.Casingsoilapplicationresultedinanincreaseintheratioofgram-negativebacterialPLFAstogram-positivebacterialPLFAs,suggestingthatsomegram-negativebacteriamightplayanimportantroleinmushroomsporophoreinitiation.
简介:Amicrobialinoculant,knownaseffectivemicroorganisms(EM),wasappliedtodetermineitsefficacyonseedgerminationandseedlinggrowthinthenurseryofAcaciaauriculiformisACunn.exBenth.Theseedlingsweregrowninamixtureofsandysoilandcowdung(3:1)andkeptinpolybags;EMwaspouredatdifferentconcentrations(0.1%,0.5%,1%,2%,5%and10%).Seedgerminationrateandgrowthparametersofseedlings–shootandrootlengths,freshanddryweightsofshootsandroots,vigor,volume,andqualityindicesandsturdiness–weremeasured.ThenodulationstatusinfluencedbyEMwasalsoobserved,alongwiththemeasurementofpigmentcontentsinleaves.Thehighestgerminationrate(72%)wasobservedin2%EMsolutionwhilethelowest(55%)wasfoundincontroltreatment.Thehighestshootandrootlengths(30.6cmand31.2cmrespectively)wererecordedin2%EMandweresignificantly(p<0.05)differentfromcontrol.Bothfreshanddryweightsofshootsweremaximum(8.66gand2.99grespectively)in2%EM,whereasbothfreshanddryweightsofrootweremaximum(2.56gand1.23grespectively)in5%EMsolution.Althoughthehighestvigorindex,volumeindex,andsturdiness(4450,628and67.5respectively)werefoundin2%EM,thehighestqualityindex(0.455)wasfoundin5%EMsolution.Thenodulenumberwashigherataverylow(0.5%)concentrationofEMbutitnormallydecreasedwiththeincreaseofconcentration.Thecontentsofchlorophylla,chlorophyllb,andcarotenoidweremaximum(43.26mg?L-1,13.56mg?L-1and17.99mg?L-1respectively)in2%EM.Therefore,lowconcentrationofEM(upto2%)canberecommendedforgettingmaximumseedgerminationandseedlingdevelopmentofA.auriculiformisinthenursery.
简介:Alaboratoryincubationexperimentwasconductedtostudytheinfluenceofcadmium(Cd),lead(Pb)andzinc(Zn)onthesizeofthemicrobialbiomassinredsoil.Allthethreemetalswereapplied,separately,atfivedifferentlevelsthatwere:Cdat5,15,30,60,and100μgg^-1;Pbat100,200,300,450and600μgg^-1andZnat50,100,150,200and250μgg^-1soil,InComparisontouncaontaminatedsoil,themicrobialbiomasscarbonandbiomassnitrogendecreasedsharplyinsoilscontaminatedwithCd,PbandZn,AmoreconsiderableincreaseinthemicrobialbiomassC:Nratiowasobservedinthemetalcontaminatedsoilsthanthenon-treatedcontrol.Amongthetestedmetals,CddisplayedthegreatestbiocidaleffectfollowedbyZnandPb,showintheirrelativetoxicityintheorderofCd>Zn>Pb.
简介:PhyllostachyspraecoxC.D.ChuetC.S.Chao,afavoredbambooshootspecies,hasbeenwidelyplantedinrecentyears.Fourstandswithdifferenthistoricalmanagementpracticeswereselectedforthisstudytounderstandtheevolutionofsoilmicrobialecologybydeterminingtheeffectsofanewmulchingandheavyfertilizationpracticeonsoilqualityusingmicrobiologicalparameters.Comparedwiththetraditionalpractice(index1),microbialbiomasscarbon(MBC)andsoilmicrobialrespirationcarbon(MRC)withthenewmanagementpracticesignificantlydecreased(P<0.01andP<0.05,respectively)with1-2yearsofmulching(index2)andthenforcontinuedmulchingsignificantlyincreased(P<0.05).TheratiosofMBC/TOC(totalorganiccarbon)andMRC/TOCalsosignificantlydiminished(P<0.05)withmulching.Theaveragewellcolordevelopment(AWCD)andShannonindexdecreasedwithmulchingtime,andthesignificantdecrease(P<0.05)inShannonindexoccurredfromindex2toindex3.Theresultsfromaprincipalcomponentsanalysis(PCA)showedthatthescoresofthefirstprincipalcomponentforindexes1and2weresignificantlylarger(P<0.05)thansoilsmulched3-4yearsor5-6years.Also,thesecondprincipalcomponentscoresforindex1werelargerthanthoseforindex2,suggestingthattheabilityofsoilmicroorganismstoutilizesoilcarbonwasdecreasingwithlongeruseofthenewmanagementpracticeandcausingadeteriorationofsoilbiologicalproperties.
简介:Inordertoinvestigatetheeffectsofmicroorganismsandtheirureaseactivitiesinmacrophyticrootzonesonpollutantremoval,foursmall-scaleplots(SSPs)ofvertical/reverse-verticalflowwetlandsweresetuptodetermine:a)therelationshipbetweentheabundanceofmicroorganismsintherootzonesandwaterpurificationefficiency;andb)therelationshipbetweenureaseactivitiesintherootzonesandpollutantremovalinaconstructedwetlandsystem.Totalnumbersofthemicrobialpopulation(bacteria,fungi,andactinomyces)alongwithureaseactivitiesinthemacrophyticrootzonesweredetermined.Inaddition,therelationshipsbetweenmicrobialpopulationsandureaseactivitiesaswellasthewastewaterpurificationefficienciesoftotalphosphorus(TP),totalKjeldahlnitrogen(TKN),biochemicaloxygendemandin5days(BOD5),andchemicaloxygendemand(COD)werealsoanalyzed.Theresultsshowedthattherewasahighlysignificantpositivecorrelation(r=0.9772,P<0.01)betweenthenumberofbacteriaintherootzonesandBOD5removalefficiencyandasignificantnegativecorrelation(r=-0.9092,P<0.05)betweenthenumberoffungiandtheremovalefficiencyofTKN.Meanwhile,therewasasignificantpositivecorrelation(r--0.8830,P<0.05)betweenureaseactivitiesintherootzonesandtheremovalefficiencyofTKN.Thus,duringwastewatertreatmentinaconstructedwetlandsystem,microorganismandureaseactivitiesintherootzoneswereveryimportantfactors.
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简介:Thepursuitofhighoilrecoveryratehasbeenapersistentobjectiveforoilindustry.Pseudomonassp.LP-7andBacillussp.PAH-2wereisolatedfromoil-contaminatedsurfacesoilsamplesofanoilfield.Theantimicrobialdegradationrates(ADRs)ofpolymersachievedbyLP-7andPAH-2wereevaluatedatatemperatureof35°Cinthemineralsaltmediaduringtheshakenflasktrial.TheADRsofcopolymersynthesizedbyusingasurfactantwithaconcentrationof5%couldreach8.4%forPAH-2and15.3%forLP-7.TheADRsofcopolymercouldreach10.4%forPAH-2and21.3%forLP-7,whenthepolymerconcentrationwas2g/L.AllresultsconfirmedthattheADRsofcopolymersincreasedwithanincreasingcontentofHDDE(capsaicinderivativemonomer)inthepolymer.ThecopolymersalsomanifestedexcellentantimicrobialdegradationperformanceinthepresenceofCu2+,Zn2+,andPb2+ions,respectively,whichhadgreatpotentialforapplicationsinenhancedoilrecovery.
简介:InordertostudytheinfluenceofdifferenceinC2H2concentrationontheproductionofCO2,N2O,NH4-Nandvolatilefattyacids(VFA).soilslurrieswithagradientinC2H2concentrationwereanaerobicallyincubatedat25℃for2weeks.Acetate,butyrateandCO2productionandNH4-NaccumulationwereinhibitedintheslurresinthepresenceofC2H2;andtheinhibitioneffectincreasedwithincreasingC2H2from0to20kPaintheheadspacegasoftheincubationbottle.However,N2O,isobutyrateandpropionateproductionwasnotobviouslydifferentamongtheslurresamendedwithC2H2from2.5to20kPa.Therefore,theresultsimpliedthattheC2H2didnotpromotetheinhibitionbutonlyincreasedthesideeffectonothermicrobialprocesses.TheC2H2of2.5kPawassuggestedtobetheoptimumchoiceforthepresentdenitrificationstudy.
简介:Thedynamicmicrocosmswereusedtoevaluatetheeffectofoilspillsonmicrobialecologicalsysteminmarinesedimentandtheenhancementofnutrientontheoilremoval.ThefunctionandstructureofmicrobialcommunitycausedbytheoilpollutionandphosphatedosageweresimultaneouslymonitoredbydehydrogenaseactivityassayandPCR-denaturinggradientgelelectrophoresis(DGGE)techniques.Theresultsindicatedthattheamountoftotalbacteriainalldynamicmicrocosmsdeclinedrapidlywithincubationtime.Thenumberofpetroleum-degradingbacteriaandtheactivityofsedimentdehydrogenaseweregraduallyenhancedbypetroleumintheoil-treatedmicrocosms,whiletheybothshowednoobviousresponsetophosphatedosage.Incomparison,phosphatespikedheterotrophicbacteriaandtheyshowedasignificantincreaseinamount.DGGEprofilesindicatedthatpetroleumdosagegreatlychangedcommunitystructure,andthebacteriabelongedtoclassDeltaproteobacteria,andphylaBacteroidetesandChlorobiwereenriched.Thisstudydemonstratedthatpetroleuminputgreatlyimpactedthemicrobialcommunitystructureandconsequentlythemarinesedimentpetroleum-degradingactivitywasenhanced.Phosphatedosagewouldmultiplyheterotrophicbacteriabutnotsignificantlyenhancethepetroleumdegradation.
简介:Microbe-inducedcalciteprecipitationisasustainableimprovementtechniqueforsandysoil,whichcanalterthepropertiesofsandviamicrobialactivity.Inthisstudy,weinvestigatedtheloose-sand-consolidationeffectbycontrollingtheinjectionvelocity,bacterialandcementingsolutionconcentrations,andholdtimes.Theresultsdemonstratethat,asthecyclicbatchincreases,theutilizationrateofthebacterialfluidincreasesandboththeopticaldensity(OD600)ofthebacteriaandureaseactivitydecrease.Moreover,itwasdeterminedthata3-hholdtimefora0.5mol/Lcementingsolutionwithacementingfluidvelocityof2mL/minhasthegreatestbondingeffect.Thefinalstrengthoftheloosesandwithanincreaseincalciumcarbonatecontentwasfurtherdiscussed.