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session 6 • Functional and structural diversity • bacteria
l B
Lactiçacid bacteria in org.nie agrfculttJral soils
SomersElen', AllamsAmke',
"'*'
Croonenborghs'.vanOverbeekLee'. YaodedeydeoJœ'
1K.U.leuven Microbial and MoIeoJlar Systems Kasteelpar Arenbe!g 20 3001 Heve.1ee. Belgium 'P1aot Research International, wageningen,theNelhlldands
According
to
a oonœpl foonulaled by H.P. Rusch (1906·1977). soli fertility of organic agriculturel soils canberelated to the presence of lac-ticacid batteria. HO'NeVer. lhere is liltle or no evidence ln literallJr8to
support lt1isronœpt.We have sampled al dilferenl lime points oyer 8 2 year period (2005-2006) 15 organic farmslnF1anders. Belgium.Soilsusedforthe orga· nieproduction
01
cabbage and Ieak~$l'Impled. Direct platingof soil dilutions oneltherMRS(withglucose ascaJ'1)onSOUrat) or M17(withlactose ascarbon),COlTI'IlOflIyused growlhmediaforlacIic
acid
bac1eria,revealed no signifiCant numbefs of IaclicacicIbacteria.ThesamereUts
Mlf8obtainedwi1hthe aJlture independenl DGGE analysis. using nested PCR 8SdescribedbyHeitigelal. (2002).identificatiOnof colonies obtained by direct plating using l.iIctobaciIus lIfOUl>specific primers for 165 rONAsequences ~1eCI maîIiy BaciIus, PHnibadIusand~spedes.lnilsecondround.an er."'ic:tmenl&teP lot IadicacidbacteriI
was
nctded.byncubating dilutecl sail samples anaerobicatyinMRSOfM17 medium. priorlapIatingorOGGE 1NlIysis.ilSdesc:riledbyChanetal(2005).ms revealedhigh~anddiYetsityoIladic aeid bac-teria.5equencingthe165rONA.te'INllId!hefoIIowWlg Iadic:aeid baderia:Lac:toooc:aIsgaMelle,LBctx:ocalS~.LlK.QltlOS/Dc
me.sen-tfHOideJ, VNi$seh,l.Bctobat::iIusWld Etltatl:lCXJ(;CUS,Sorneofthese isoIateswetetestedanclbJndposiWeb biocontIolacrMtyandIor cfirecl: plant
wowth
promotion.TwoUdococaIiI8ctis
isolalesshowedsignificantplanlgrow\hpromotiflgaclMtyin greeMousetria\$with"'--.
Il canb8eoncIudedlhallacticaadbacteria,althoughpresent.areJ'lOtOominanllnorganlcfarmingsoilsinRanders.
Nevertheless,iftheycanb8enrichedltlrough agriaJltural Pf3C\icas.sorne oflheseshowpotenlialforbioalnlroland/orplantgi'OWlhpromotion. Heilig el al(2002) Appl.Environm.Microbiol. 68.114·123.
Chenetal(2005) Lelt. Appl.MiC1Obioi.40. 195-200.
Rusch H.P. (1964) Bodenfruchbar1leij.Kart F. Hauh Vertag,ed.(Heidelberg).
am
Symbiotic and ph)40genetic diversity of rhizobia associated
with
native and introduced Acacias in Alg.na
BoukIIalemZinebFm,Dome~Ollie.GalianaAntoine.DeLajudiePhilippe.LaguerreGiMle. BekkiAbdIIbder.Ge!jlMAntoDa
~clesSyntJio$esT~ et~UMR 113ClRADIJRD/INRAI SupAgroJUMlI, 34398MonlpeIierCedex5. Franœ
lnthearidzoneswtIete
aop
producü:lnIsredl.œddueto
Qoouglltcombinedto
Iow soi!lertiity,theuse of~nativeIegumenes adaptedto
suctl haf5htXlidlîonsooukIenhanc::e thepmdtJdiyiyofagroIorestry systems.InNorthAfrica,Acade speciesare goocI c:andida-tes b thisplSpOSesinœtheycantFJW
onN-deficienl50ÎISand~lheirNbaJal'lOllduetetheirS)'ITlbiollcassociationwîlh rhizobia,~soibadetîa.
ln Ofder10ldentifyandseled. ellicienlacaCia-rtlizcbia syntIioticassociations.soi! sarnplesandroolnodulesFrom seven Acaciaspecies,l1ve nativelAehtenbet'giBna,A
htet.,
A.niIotica,A. seyaf, A.tortis)andIwointroduœd (A.kanoo,A.SB6gna).were coIlected irl arid and seJri.arid regionsofAIgeriafromOran
to
TamanrassetAroIIectionof22 bac1eria1strainsWBSobtained aftet trapping onAc.cia
seedlings inocu-laledwilhsolisamples originating from nine geographic siles.165tONAiequencing reveal8dlhal thenew
strains repteS8l1led dilfll1"enl spa-cles in Slnorfllzobium and Rhizobium. This genetic diversity WBS confirmedby phenotypicch&racterisation through biochemical assays and host spec\Nm.Somastrains were partieularty tolerantlo loWpHand high NaCI c:oncentralions. temperature and osmotic slress in in vitro condttions. In a neKt slep, selectionofelTicienl rtlizobia displaying a high nitrogen-fixing polential uOOer stress conditions willbecanied outinconll'Olled conditions before lasting ltlem in fietd conditions.
116
liID
Genttlc:
diversfty of rhizobia that nodulate
Prosopis jullfkJnl
in the and 'Istem arel of Morocco
Btna!B
Hlrww·Ou~MoIammed.Bemc:hiAbdebasset,Abdel~menHanaiI,8ouktlal6mNoumIddine. Missbah ElkIriuît.\Wapl'la~MchamedPremier, F... ôesac:iences. e>..;ciaBiokJgieL..alxnlonde BiOklgie ôesfltantesetdes~ s .FacU'.6deS
SCIen-ces ,Oujda60.000 OujclaMoroc:co
5ymb1cticnilrogenfixation
n
!he aridregions dependson
!heIwopartnInofthesyrnbiO$iS:Iegume -
Itizotlium andIheiri<ptitude10aaapl
teprev;iIing ctmalicandsolCMStrMlts.Vieshowed!hal ProsopisjcJiItxaisa sallolefant~species, moait is
net
aftededby the sanc:oncenntiOnsas high as seawaterIevels.This plant repraserns a verygoodcandidateteoombatdesel1il'icalion.we
lhusisolated214 bac:l&rial strainsfromtherootnodu6esri
PtosopisjuIifIora,euItivatedindilfetenl soilsri
theEastem areaofMotoeco.
Wefoundlhal 24 strains IoIerated NaCI cooœnlr.Jtions highef than 30~(w/v). AMthestrains re-oodulatedtheiroriginals hosl They aH pœ-sessedthenodCgane. This wascheckedbyamplifyingthenodC genewhichcodesfora NodC nodulalionfactorbyPCRspecifieprWners. Theassessmentofmetabolic and physiologie properties 01\he$eisolaleshoweda hlgh phenotypic diversity.thisIs an advantage forthe plant b&cause~can be always nodulaledbydiflerent types 01 rtlizobia even ifthesoil or climate conditions have to change.
The RFlPofthe165 fONA using Mspl. Haelll and Cioi enzymes oonfinnedthedivel'Sity ofthestrains!hat oodulate thls specias inthesame
solI.We Illus obtalned lhree difterenl profiles.Thedivefsity cithestrains was alsa assessedbytheBllpIoralionofthebaeterial chromosome eatried