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低温异养硝化细菌的筛选及其固定化研究 Title:ScreeningandImmobilizationofPsychrophilicAutotrophicNitrifyingBacteria:AStudy Abstract: Psychrophilicautotrophicnitrifyingbacteriaplayavitalroleinnitrogentransformationprocessesatlowtemperatures.Thisstudyaimstoscreenforsuitablestrainsofthesebacteriaandevaluatedifferentimmobilizationmethodsasameansofenhancingtheirstabilityandperformance.Theresultsofthisresearchwillcontributetoimprovingourunderstandingoflow-temperaturenitrificationprocessesandprovideinsightsfortheirpotentialapplicationsincoldenvironments. 1.Introduction Nitrificationisacriticalprocessinthenitrogencycle,inwhichammoniumisoxidizedtonitritebyammonia-oxidizingbacteria(AOB)andfurtherconvertedtonitratebynitrite-oxidizingbacteria(NOB).However,traditionalnitrifyingbacteriaaremesophilic,andtheirefficiencydecreasessignificantlyatlowtemperatures.Therefore,theisolationandscreeningofpsychrophilicautotrophicnitrifyingbacteriabecomesessentialforthesuccessfulimplementationofnitrificationprocessesincoldenvironments. 2.Methodology 2.1ScreeningProcedure: (a)Samplecollection:Sedimentsampleswerecollectedfromvariouscoldenvironmentssuchaslakes,rivers,andglaciers. (b)Enrichmentculture:Sampleswereinoculatedintoamineralmediumandincubatedatnear-optimallowtemperatures. (c)Determinationofnitrifyingactivity:Theenrichmentculturesweremonitoredfornitrificationactivitybymeasuringtheproductionofnitriteandnitrate. (d)Isolationandidentification:Individualcoloniesshowingnitrifyingactivitywereisolatedandidentifiedbasedontheirmorphologicalandgeneticcharacteristics. 2.2ImmobilizationTechniques: (a)Alginateimmobilization:Cellswereimmobilizedinalginatebeads,allowingfortheirretentionwhileenablingnutrientandsubstrateexchange. (b)Biofilmimmobilization:Cellswereattachedtoasolidsurface,providingahighsurfacearea-to-volumeratioandpromotingcell-cellinteractions. (c)Carrier-basedimmobilization:Cellswereimmobilizedonasupportmaterial,enhancingtheirstabilityandprotectionagainstexternalenvironmentalconditions. 3.ResultsandDiscussion