Growth characteristics and chemical compositions of Phaeodactylum tricornutum under different nitrog

Phaeodactylum Growthcharacteristicsandchemicalcompositionsof tricornutum underdifferentnitrogenconcentrations * CAIZhuoping,DUANShunshan InstituteofHydrobiology,JinanUniversity,,GuangzhouChina Phaeodactylumtricornutum Abstract: Themarinediatomaphytoplanktonspeciesthatcontainsahighcontentofbioactive is compoundsandthusitcanbeservedasanimportantfoodsourceandfeedadditiveinthesuccessfulrearingofaquaticanimalslike shrimpandfish.WhileitsoverproliferationalongthecoastalareasofChinainrecentyearshasbroughtaboutmanynegatively environmentalandeconomicconsequencesaround.Inordertoinvestigatetheeffectsofdifferentnitrogenconcentrationsonthe Phaeodactylumtricornutum growthcharacteristicsandchemicalcompositionsin,algalcelldensity,specificgrowthrate,biomass, andthecontentsofsolublesugar,proteinandchlorophyllahavebeenexaminedinlaboratoryculturesbyemployinglownitrogen -1 -1 -1 (LN,44µmol·LNaNO),mediumnitrogen(MN,880µmol·LNaNO)andhighnitrogen(HN,400µmol·LNaNO) 4 3 3 3 Phaeodactylumtricornutum concentrations.Ourresultsindicatedthatthegrowthcurve,specificgrowthrateandcellbiomassofwere 4-1-1-1 significantlyaffectedbynitrogenconcentrations.Theywere149.510cells·mL,0.37d,and209.33µg·mLunderLN 0× 4-1-1-1th condition,whereastheywere951.610cells·mL,0.67d,and806.00µg·mLunderHNconditionatthe10dayduringthe 7× stationaryphase.AlthoughHNtreatmentsignificantlyenhancedthealgalcellnumberandcellyieldinthestationaryphase,itdidnot showremarkabledifferencesinthegrowthcurveandspecificgrowthrateintheearlystagesascomparedwithMNtreatment. Besides,thecontentsofsolublesugar,proteinandchlorophyllawereobviouslyincreasedwiththeincreasingofnitrogen concentrations,whichwereapproximately2.5,1.5and15timeshigherinHNtreatmentthanthoseinLNtreatment,respectively.It canbeconcludedfromthepresentinvestigationthathighernitrogenconcentrationscanacceleratethegrowthanddivisionaswellas Phaeodactylumtricornutum biosynthesisofsomechemicalcompositionsof,andthereforethisshouldbetakenintoaccountforthe prevalenceofredtidesdominatedbythismarinemicroalgainrecentyears. Phaeodactylumtricornutum Keywords: nitrogenconcentrations;growthcharacteristics;chemicalcompositions; CLCnumber:Documentcode:ArticleID: X173A1672-2175200706-1633-04 （） Aslongasalgalgrowthisnotoverprolificinthewater, tideoccurredalongthecoastofHainanprovincealsoduetothe algaeareofbenefittomarinecultureoperationsbecausethey overproliferationofthismarinemicroalga,whichpotentially areprimaryproducersintheoceans,ensuringtheaquaticfood destroyedthenaturalmarineecosystemsaroundandinflicted [1] supplyfromthoseproducersissustainableandplentiful. significantlynegativeimpactsonthesociety,witha Sometimes,unfortunately,somespeciesofalgaeproliferate tremendouseconomicloss.Ontheotherhand,somestudies quicklyinsuchlargenumbersthattheycangivebrownish implicatedthatnitrogen,anessentialelementforplantgrowth, yelloworreddishcolortotheentirebodyofwaterdepending couldbeinvolvedinphytoplanktonproliferation,whichledto [2-3] [12-13] onthealgaeinvolved,whichisbestknownasredtides.It theoccurrenceofredtidesaroundtheglobe.Likewise, hasbeenwelldocumentedthatredtideshaveincreasedin somestudiesalsoimplicatedthatexcessiveNnutrient frequency,intensityandgeographicdistributionduringthelast enrichmentviaindustrialandagriculturalinputscouldbea [4-5] [14-15] decadesandthattheyhavebroughtaboutmanynegatively majorbasisintheincreasedprevalenceofredtides.Inthe [6-8] environmentalandeconomicconsequences.Themarine Phaeodactylumtricornutum currentstudy,marinediatomwas Phaeodactylumtricornutum diatomisaphytoplanktonspecies subjecttovaryingNconcentrationsinlaboratorycultures.The thatcontainsahighcontentofbioactivecompoundsand objectivesoftheexperimentspresentedhereweretoexamine polyunsaturatedfattyacids(PUFAs),suchaseicosapentaenoic theeffectsofNconcentrationsonthegrowthcharacteristicof acid(EPA)anddocosahexaenoicacid(DHA),andthusitcan Phaeodactylumtricornutum ,andtocharacterizethechangesof beservedasanimportantfoodsourceandfeedadditiveinthe somechemicalcompositions,includingsolublesugar,protein [9-11] successfulrearingofaquaticanimalslikeshrimpandfish. andchlorophyllaundervariousNconcentrations,thustrying However,earlierobservationshaverevealedthat togathersomebasicphysiologicalandbiochemical Phaeodactylumtricornutum wasresponsiblefortheredtides informationofthismicroalga. occurredinShangdongprovincein1995,andthatin2006ared 1Materialsandmethods