Successful-bacterial-incorporation-into-activated-sludge-flocs-using-alginate

ShortCommunicationSuccessfulbacterialincorporationintoactivatedsludgeflocsusingalginateT.Boucheza,b,*,D.Patureaua,J.P.Delgenèsa,R.MolettaaaInstitutNationaldelaRechercheAgronomique,LaboratoiredeBiotechnologiedel’Environnement,AvenuedesEtangs,11100Narbonne,FrancebCemagref,URHBAN,ParcdeTourvoie,BP44,F-92163AntonyCedex,FrancearticleinfoArticlehistory:Received16August2006Receivedinrevisedform15July2008Accepted16July2008Availableonline29August2008Keywords:BioaugmentationAlginateMicrovirgulaaerodenitrificansAerobicdenitrificationFluorescentinsituhybridizationabstractBioaugmentationexperimentswiththeaerobicdenitrifierMicrovirgulaaerodenitrificanswereperformedinanaerobiccontinuousstirredtankreactor(CSTR)treatingurbanwastewater.Thefateoftheaddedbacteriawasmonitoredbyaspecificfluorescentoligonucleotideprobetargeting16SrRNA.Thefirstaddi-tionofthestrainledtoitsrapiddisappearancebecauseofgrazing.Bacteriawerethenembeddedwithinanalginatematrixbeforeinoculation.Alginatefragmentsadheredtotheexistingflocsandwereprogres-sivelycolonizedbytheindigenousflora.Thereafter,microcoloniesoftheexogenousbacteriumwerefoundtobeincorporatedintoexistingflocs.�2008ElsevierLtd.Allrightsreserved.Bioaugmentationistheadditionofaselectedbiomassinordertoinduceorenhancecertainbiologicalpropertiesinanecosystem(StephensonandStephenson,1992).Inthefieldofwastewatertreatment,theeffectsofsuchaprocedurearecontroversial.Bio-augmentationfailurewasreportedasoftenasitssuccess(BeliaandSmith,1997;Lanthieretal.,2002;Loperenaetal.,2006,2007;Oertheretal.,1998).Themajorreasonliesonthefactthattheevolutionofthesystem’sperformancesshouldnotbeconfusedwiththefateoftheaddedmicroorganisms,whichhastobeinde-pendentlymonitored(ElFantroussiandAgathos,2005).Thebio-logicalphenomenaleadingtothesuccessofthebioaugmentationprocedureindeeddependonthetypesofbiologicalmaterialsusedforbioaugmentation.Whengeneticallyengineeredmicroorgan-isms(GEM)areemployed,theycanactasadonorofcatabolicgenestounknownindigenousrecipients,especiallybyplasmidtransfe