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JOURNALOFBrOSCIENCEANDBrOENGINEERING 。206，Th巴 SocietyforBiotechno1ogy，Japan Vo.l101，No.6，478-484.206
DOI:1O.1263/jb.101.478
Inf1uenceofTemperatureonGrowthofLegionelapneumophila BiofilmDeterminedbyPreciseTemperatureGradientIncubator
TadashiKonishi，1*TetsuYamashiro，zMichioKoide，3andAkiraNishizono1
FacultyofMedicine，OitaUniversi，yt lIdα，i-gaoka，Yufu，Oita879-5 593，Japan，1InstituteofTropicalMedicine， NagasαkiUniversity，1-12-4Sakamoto，Nagasaki852-8523，Japan，2andFacultyofMedicine，
UniversityoftheRyuかus，1Senbaru，1¥Tishihara，Okinawa903-0213，Japan3 Received27D巴cemb巴r205/Acepted2March206
Bacterialgrowthisinfluencedbyseveraldiferentcultureconditions.Temperatureisoneofan
esentialcomponentwhichregulatesbacterialgrowthandtheirmorphology.Theinfluenceof
temperatureonthelengthofbacteriawasinvestigatedinbrothandonagarinatemperature
rangefrom30.0oCto47.0oCin0.50Cstepsusinganewlydevelopedtemperaturegradientincuba-
tor.Theincubatorisabletoreachasettemperaturewithin2handmaintaintemperatureasacu-
rateas:t0.1oCofthesettemperature.ThreeLegionelapneumophilasero句rpe1strainswereincu-
batedfor48hinBCYE-αagaratvarioustemperaturesrangingfrom30.0oCto48.0oCandlength
ofbacteriagrownateachtemperaturewasmicroscopicalymeasured.Abilityofbacteriatomul-
tiplyatagiventemperaturewasalsodetermined.L.pneumophilaserotype1strainsATCC33152，
aclinicalisolateOkinawa02-0.1weregoingtoelongatetolongerthan100μmwhencultured
higherthanat39.50C andat41.50C，respectively.Eachstrainwasunabletomultiplywhencul- o
turedhigherthanat4.20C(ATCC3152)orat4.0C(Okinawa02-01).Thosedatawouldpro- videinsightsforestablishingregulationsintermsofmaintaininghotwatertemperatureinafacil- itywhereacirculatinghotwatersuply-systemisavailableandcontaminationwithLegionela sp.islikelytohappen.
[Keywords:Legionelapneumophila，biofilm，temperaturegradientincubator，celelongation]
BacteriaofthegenusLegionelaaregram-negative，aero- bic，androd-shapedwithoneormorepolarflagela(1，2). Legionelapneumophilaisconsideredtobeanimportant etiologicmicrobialagentoflowerrespiratorytractinfec- tionsintheUSorinWesternEurope，acountingfor2%to 8%ofalcasesofcomunity-acquiredpneumonia，second onlyinimportancetoStreptococuspneumoniσ(3).The numberofLegionelasp.asociatedwithpneumoniawas rarelyreportedinJapanuntilApril19，whenanewLaw ConcerningthePreventionofInfectiousDiseasesandPatients withInfectiousDiseases(NewLawonInfectiousDiseases) wasenacted.ThelawclasifiedLegionelapneumoniaasa nationalynotifiableinfectiousdisease，withmandatoryre- portingofeverycaseofLegionelapneumoniatotheMinistry ofPublicHealthandWelfareviaaprefecturalhealthcenter. ThenumberofreportedLegionelapneumoniacaseshas sinceincreaseddramaticaly:53casesin1999，151casesin 2000，and83casesin201.In2002，anoutbreakoflegion- elosisocuredatapublicbathouseinMiyazaki，Japan.In theoutbreak，32caseswerelaboratoryconfirmedasLegion- elapneumoniaand263casesweresuspect.
Legionelasp.arecommonlypresentinnaturalandman madeaquaticenvironments(4-6).Thebacteriaproliferate instagnantwarmwater，asfoundincolingtowers，certain
*Corespondingauthor.e-mail:konishi@med.oita-u.acj.p phone:+81-(0)975-586-5712fax:+81-(0)975-586-5719
plumbingsystemsandevaporativecondensersoflargeair-
conditioningsystems.Outbreaksoflegionelosishaveocur-
redwhenpeoplehaveinhaledaerosols企omwatersources
contaminatedwithLegionelabacteria(7).Inthesecondi-
tions，thebacterialcountwouldreach103-106cfuml-1，much
higherthanthatseninthenaturalenvironment.Incirculat-
ingwatersystems，legionelaearemostfrequentlydetected
inbiofilmsinplumbingfixtures(5，8-10).Biofilmhasapo-
tentialroleasavehicletoconveylargenumbersofembed-
dedbacteria，causingpneumoniawhenaerosoldropletscon-
tainingfragmentsofbiofilmareinhaledbyhumans(1).In
flowingplumbingsystems，temperaturegradientsareformed
over a solid wal l due to the tempera印 re dif ference between
hotwaterandtheambientenvironment.Asscale(suchas
silicacompounds)，debris，biofilmorsedimentadheretothe
pipewal，radialtempera加 regradientsareformedinsidethe
biofilm.Variousdisinfectionmeasurestopreventlegionel-
losishavebeenused(12-15).Legionelae訂 esensitiveto
tempera加 re(16-21)andchlorine.Legionel laegrowpo orly
attempera同 resbelow200C orabove500C andareeasily
kiledattemperaturesabove60oC.Inhospitalorpublic
water，systemsLegionelaecanbekiledbyraisingthetem-
peratureofthehotwatersuplyto700Cto800C(2，23).
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InJapan，govemmentregulationsrecommendanoperating o
tempera同 re ranging from 500 C to 60 C.Legionel lae are alsosusceptibletochlorine-andbromine-containingcom- pounds，ozone，heavymetalions，andultravioletlight(21，
