2005-Anaerobic-ammonium-oxidation-(anammox)-in-the-marine-environment

ResearchinMicrobiology156(2005)457–464www.elsevier.com/locate/resmicMini-reviewAnaerobicammoniumoxidation(anammox)inthemarineenvironmentTageDalsgaarda,∗,BoThamdrupb,DonaldE.CanfieldbaNationalEnvironmentalResearchInstitute,DepartmentofMarineEcology,Vejlsøvej25,P.O.Box314,8600Silkeborg,DenmarkbDanishCentreforEarthSystemScience,InstituteofBiology,UniversityofSouthernDenmark,Campusvej55,5230OdenseM,DenmarkReceived27October2004;accepted19January2005Availableonline17March2005AbstractAnammox,anaerobicammoniumoxidationwithnitrite,isnowrecognizedasanimportantprocessinthemarinenitrogencycle.ThebacteriaconductinganammoxarehighlyspecializedandappeartobelongtothePlanctomycetales.Theprocesshasnowbeenfoundinarangeofenvironmentsincludingmarinesediments,seaiceandanoxicwatercolumns,anditmayberesponsibleforupto50%oftheglobalremovaloffixednitrogenfromtheoceans.2005ElsevierSAS.Allrightsreserved.Keywords:Anaerobicammoniumoxidation;Anammox;Review1.IntroductionAlreadydecadesago,therewereseveralindicationsthatNH+4couldbeoxidizedanaerobicallyinnature.Forexam-ple,in1941anaerobicNH+4oxidation(nowcalledanammoxwhencoupledtoNO−2reductionasexplainedinSection3)wasadvancedasapossiblesourceofN2inthesea[11].LaterobservationsfromanoxicwatercolumnsindicatedthatNH+4disappearedunderanoxicconditions[3,20,21],andtheoxidationofNH+4withNO−3toformN2wastheexplana-tionmostconsistentwiththedata.Similarobservationsweremadeintheanoxicsulfide-freeportionofthewatercolumnintheBlackSea[18].Here,NH+4transportedfrombelowdisappearedbeforeitmettheO2intheoverlyingwater,andtherewasaca.20mthickzonefreeofbothO2,NH+4andH2S.Nitratewaspresenthere,anditwassuggestedthatNH+4wasoxidizedwithNO−3,preventingtheNH+4frommeetingtheO2.InmarinesedimentstheoxidationofNH+4withNO−3hadalsobeeninvokedtoexplaintheanoxicdis-appearanceofNH+4[1,16,27].Moreover,calculationsof�GvaluesfortheoxidationofNH+4withNO−3showedthatthe*Correspondingauthor.E-mailaddress:tda@dmu.dk(T.Dalsgaard).processwasenergeticallyfavorable[2,3],yetanotherreasontoexpectitmight