Adaptation of Rhizobium bacteria depends on the short- or long-term
effects of heavy metals
Borbala BIROBorbala BIRO
Laboratory of RhizobiologyLaboratory of Rhizobiology
Research Institute for Soil Science and Agricultural Chemistry
Hungarian Academy of SciencesHungarian Academy of Sciences (RISSAC)(RISSAC), Herman O ut 15, H-1022 , Herman O ut 15, H-1022
Budapest, Hungary. Budapest, Hungary. E-mail: E-mail: [email protected]@rissac.hu
Adaptation as a tool of sustainabilityAdaptation as a tool of sustainability
Adaptation - better tolerance of Adaptation - better tolerance of environmental (stress)factorsenvironmental (stress)factors
Adapted microbes confer their tolerance Adapted microbes confer their tolerance to the non-adapted plants (crops) – best to the non-adapted plants (crops) – best „„strugle for life strategystrugle for life strategy” of both ” of both partners!partners!
New generation of microbial inoculums? New generation of microbial inoculums? But how the adaptation developes?But how the adaptation developes? Do adapted microbes functioning Do adapted microbes functioning
well?well?
Inoculated Non-inoculated
12 weeks old tomato plants grown in heavy metal soil with or without metal(Zn)-adapted
mycorrhiza (Glomus sp. Br1)
Discrepances at metal effects!
1 µM ZnSO4
100 µM ZnSO4
500 µM ZnSO4
1 mM ZnSO4
Root-organ carrot inoculated with Glomus intraradices Sy167
Growth as a function of the applied rates!
Better growth at the 2nd ratio!
1µM ZnSO4100 µM ZnSO4
Hyphal biomass 80mg
500 µm
160mg
500 µm
Discrepances at metal effects!Double biomass, but low sporulation (reduced fertility?)!
Discrepancies between adaptation Discrepancies between adaptation and functioning (Summary)and functioning (Summary)
Adaptation: Adaptation: better metal tolerance!better metal tolerance! enhanced growth even for the host-plant!enhanced growth even for the host-plant! But!But! Altered other ecophysiological parameters Altered other ecophysiological parameters
((sporulationsporulation, infection ability – , infection ability – effectivityeffectivity, N, N22--fixing or P-mobilising ability – fixing or P-mobilising ability – efficiencyefficiency))
In a multifactorial system any In a multifactorial system any parameters have his own „private life”parameters have his own „private life”Needs for modell experimental background!
Introduction and hypothesis NN22-fixing (bioferilizer) bacteria-fixing (bioferilizer) bacteria are are
important element of soil-fertility! important element of soil-fertility! Some Some adaptation is necessary in the polluted adaptation is necessary in the polluted soil soil (microbial inoculums)!(microbial inoculums)!
But! But! How the adaptation developes?How the adaptation developes?How the adaptation is depending on:How the adaptation is depending on: the affectingthe affecting periods? periods?oror the affecting the affecting doses? doses?
Materials and methods
Modell experiments:Modell experiments: Long-termLong-term ( (16 year16 year) application in ) application in
(Braunschweig field study with (Braunschweig field study with sewage sewage sludgesludge) )
Short-termShort-term ( (4-year4-year)pot experiment with )pot experiment with sludgesludge (RISSAC, Budapest) (RISSAC, Budapest)
Long-termLong-term, , only metal-salt only metal-salt experiment (experiment (13 13 metals, 4 dosesmetals, 4 doses) – (RISSAC, ) – (RISSAC, Nagyhörcsök) Nagyhörcsök)
Materials and methods
NN22-fixing -fixing Rhizobium Rhizobium strains:strains: Control (only fertilizer, no sludge, no Control (only fertilizer, no sludge, no
metals)metals)
Long(slow)-adapted strains (16-years) Long(slow)-adapted strains (16-years) Short(fast)-adapted (1.-, 4.-years Short(fast)-adapted (1.-, 4.-years
isolates)isolates)
Short-term effect of Zn-containing sewage sludge
0 7.5 15 30 60 t/ha
Studies on the root-nodulation an on the Rhizobium isolates
Rhizobium – Zn Long-(16-years)-adaptation
Adapted Rhizobium
40
60
80
100
120
140
160
180
0 1 2 3 4 5Concentrations
Rela
tive
grow
t (%
)
Non adapted Rhizobium
40
60
80
100
120
140
160
180
0 1 2 3 4 5Concentrations
Rela
tive
grow
th (%
)
Stimulation Retardation
0 0.1 1 10 100 1000 mg.L-1
Zn become non-essential and less-dependent on the doses with a reduced growth-ability!
Rhizobium - CuLong-(16-years)-adaptation
Non adapted Rhizobium
0
20
40
60
80
100
120
140
0 1 2 3 4 5Concentrations
Rela
tive
grow
th (%
)
Adapted Rhizobium
0
20
40
60
80
100
120
140
0 1 2 3 4 5Concentrations
Relat
ive g
rowt
(%)
0 0.1 1 10 100 1000 mg.L-1
tolerantsensitive
Less dosis-dependence, better growth at highest rates
Rhizobium – Zn Short-(4-years)-adaptation
2000/Zn
4
6
8
10
12
14
kontrol 45 90 180 360 720Concentrations (mg.l-1)
LgCF
Uml-1
2002/Zn
4
6
8
10
12
14
kontrol 45 90 180 360 720Concentrations (mg.l-1)
LgCF
Uml-1
Zn become more toxic at the higher doses!
Tolerant Sensitive
Rhizobium – CrShort-(4-years)-adaptation)
Cr/2000
4
6
8
10
12
14
kontrol 37,5 75 150 300 600Concentrations (mg.l-1)
LgCF
Uml
-1
Cr/2002
4
6
8
10
12
14
kontrol 37,5 75 150 300 600Concentrations (mg.l-1)
LgCF
Uml-1
Cr become more toxic at the higher ratios!
tolerant sensitive
Summary Summary ShortShort and and longlong-term effect of metals-term effect of metals
A clear dosis-dependence was found! A clear dosis-dependence was found!
Slow releaseSlow release of below toxic levels of below toxic levels might might increse the adaptationincrese the adaptation to the toxic ratios! to the toxic ratios!
The adaptation is a The adaptation is a process in timeprocess in time and and might enhance the behaviour and „strugle might enhance the behaviour and „strugle for life” success of microbes! for life” success of microbes!
háttér-érték
tulajdonság
adaptáció toxikusság
növekvő stressz vagy szennyeződés
javuló tulajdonság
A környezeti alkalmazkodás folyamata
Adaptáció és szennyeződésAdaptation in timeAdaptation in time
Better tolerance for a certain limits!
Conclusion - I
Take care of the affecting doses! Take care of the affecting doses! The sensitivity is incresing at The sensitivity is incresing at
beyond-tolerable levels! beyond-tolerable levels!
Enhanced selection pressure on the Enhanced selection pressure on the population! population!
Conclusion - II
According to Puskin, According to Puskin, Minden az „Anyegin” Minden az „Anyegin” múlikmúlik” („things are highly dependent on ” („things are highly dependent on the the moneymoney”?)”?)
In our caseIn our case::
((It is a fortune, that microbe behaves differentlyIt is a fortune, that microbe behaves differently))
The adaptation success is highly The adaptation success is highly dependent on the:dependent on the:
Affecting periods at a certain Affecting periods at a certain metal-metal-type type (Zn) at a certain (Zn) at a certain metal doses! metal doses!
Acknowledgement!
MTA TAKI for experimental background MTA TAKI for experimental background (Imre (Imre KÁDÁR, Tamás NÉMETH)KÁDÁR, Tamás NÉMETH)
Support of the Hung. Res. Fund (OTKA)Support of the Hung. Res. Fund (OTKA) Spanish, Swiss, Austrian, Russian – Spanish, Swiss, Austrian, Russian –
bilateral collaborationsbilateral collaborations Hungarian parners of studies (NyF, Hungarian parners of studies (NyF,
Nyiregyháza, SZIE, Gödöllő), Nyiregyháza, SZIE, Gödöllő),
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