SIGNIFICANCE, MECANISMS AND ENVIRONMENTAL IMPLICATIONS OF MICROBIAL BIOMINERALIZATION ... ·...
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200 nm 1 μm200 nm
SIGNIFICANCE, MECANISMS AND ENVIRONMENTAL IMPLICATIONS OF MICROBIAL BIOMINERALIZATION
PROCESSES
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

[As] ≤ 1mg/l
[As]= 300 mg/l
1 m
Acid Mine drainage: Carnoules (France)
Pb-Zn abandonned mineWater pH~3
20-60% As removed after 30 m of downflow
Leblanc et al. Appl. Geochem. 1996Casiot et al., Water Res. 2003Casiot et al., Sci Total Environ 2005
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

1 m
As(III) tooeleite
As is trapped by the formation of diverse As-Fe-rich minerals (up to 22% As)
Amorphous As(V)-Fe(III)
2L-ferrihydrite
Schwertmannite
10 30 50 70 90
Diff
ract
ed in
tens
ity
Co K α 2θ (�)
* sample holder
Qz
**
*
tooeleite
As(III)/Fe = 0.60
As(III)/Fe = 0.42
As(V)/Fe = 0.72
schwertmannites
As(III,V)/Fe = 0.16
As(III,V)/Fe = 0.30
As(III,V)/Fe = 0.07
2L-ferrihydrite
As/Fe = 0.01
tooeleite
amorphous + to
amorphous
0.20
Morin et al., ES&T 2003
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Microbes indirectly impact the formation of minerals by redox transformations
Fe2+ + As3+ + SO42- + H2O + O2 Fe(III)-As(III) phase (Tooeleite)
Fe(III)-As(V) amorphous phase
Fe oxidizers
As- and Fe-oxidizersFe2+ + As3+ + SO4
2- + H2O + O2
+ CO2 + CH2O
Thiomonas sp.
AmorphousFe(III)-As(V)
1 µm
A. Ferrooxydans strain
tooeleite
1 µm
Metabolic activity catalyzes the formation of mineralsColloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

1 m
As(III) tooeleite
Diversity of minerals results from the diversity of bacteria
Amorphous As(V)-Fe(III)
2L-ferrihydrite
Schwertmannite
X-Ray Diffraction and XAS: (e.g. Morin et al. ES&T 2003; Morin et al. Am Min 2007)
Spatial and temporal variation of the mineralogy of sediments
Bruneel et al. (2006) AEM
Microbial diversity:→ Low diversity→ Species able to oxidize Fe/ As→ Spatial and temporal variations of thesecommunities
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Use of microscopy to look at microbial precipitates
Synchrotron-based X-ray SpectromicroscopySTXM
Transmission Electron Microscopy
Need to characterize both organics and minerals at the submicrometer scale
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Scanning Transmission X-ray Microscope
detector
sample
monochromaticX-ray beam
Objective= Fresnel lens
Aperture
He, air or vacuum
x
y
Microscopechamber
280 285 290 295 300
XANES C K-edge
Photon energy (eV)
Images with 20 nm resolution
High spectral resolution XAS By tuning incident energy : study of C, Fe, As
speciation
Synchrotron= source of high brightness X-ray radiations
500 nm
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Mapping As redox in Carnoules sediments at the 50-nm scale
2 μm
STXM image
2 μm
As map
2 μm
As(III)As(V)
Energy (eV)
1320 1330 1340 1350 1360 1370
1329.9eV1326.5eV
X-r
ay A
bsor
ptio
n
Amorphous As(V)-Fe(III) phase
TooeleiteFe6(AsO3)4SO4(OH)4,2H2
O
XANES As L3-edge
As(III)
As redox map
2 μm
STXM bacteria map
Difficult to evidence a correlation between As redox and specific microorganisms
Benzerara et al. GCA 2008
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

TEM on thin section
400 nm
Bacterial cell
Bacteria cell walls provide nucleation sites for the precipitation of Fe-As minerals
500 nm
200 nm
1. Diverse patterns of biomineralization2. Fossilization of microorganisms
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

However, most of the precipitates are extracellular…
1280 285 290 295 300 305
Energy (eV)
284.4285
287.6
288.5 290.7
Likely significant impact on sedimentation properties, maybe surface reactivity?
5 μmOrganic C map
STXM at the C K-edge shows the presence of pervasive organic carbon polymers
Abs
orpt
ion 284.4 eV: 1s-π* quinone
285 eV: 1s-π* aromatics287.6 eV : 1s-π* ketone288.5 eV: 1s-π* carboxylic
290.7 eV: 1s-π* Fe-carboxylics
Benzerara et al. GCA 2008
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

100 nm
Abundance of mineralized vesicles in Carnoules: An overlooked biomineralization process ?
400 nm
TEM on thin sectionTEM
Bacterial cell
1 μm
SEM
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

What do we learn?
Microbes and mineral precipitation:
indirect role via metabolic activity
nucleation surfaces: cell wall, extracellular polymers, vesicles
What needs to be further studied?
How bacteria deal with mineral precipitation?
→ Is it lethal? → Beneficial? → Are there adaptative responses to mineral precipitation?
Why are there different biomineralization patterns?
What are the molecular mechanisms of these biomineralization processes?
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Precipitation of minerals and Bacteria
Advantageous:
Production of H+ used for energy generation
Protection against antibiotics/radiation/dessication/toxic metals…
Magnetic sensing (e.g., magnetotacticbacteria)
Lethal:
Disruption of membranesLimitation of nutrient transfers
Some microbes develop strategies to limit precipitation within the cell
100nm
From Nicolas Menguy (IMPMC)From Jennyfer Miot (IMPMC) From Xavier Chatellier (CAREN, Rennes)
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

EXPERIMENTAL APPROACH
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Experimental Fe biomineralization by neutrophilic anaerobic bacteria
Dilemma: source of energy but production of a highly insoluble compound
Fe(III)Fe(II)bacteria
pH = 7
4 Fe2+ + 11 H2O + CO2 4 Fe(OH)3 + 8 H+ + CH2O2 Fe2+ + 5 H2O + NO3- 2 Fe(OH)3 + 4 H+ + NO2
-
Encrusts
1 µm
BoFeN1
Does not encrust
1 µm
SW2
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Fe biomineralization by BoFeN1 (encrusting cells)
0
10
20
30
40
50
60
70
0
1
2
3
4
5
6
0 50 100 150
prot
ein
conc
entr
atio
n (m
g.m
L-1
)
Dissolved
Fe(II) concentration, mM
Time, hours
Biomass
Fe(II) concentration
t = 0 t = 3d t = 6d
• Where is Fe(II) oxidized?• Where does Fe(III) precipitate?
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Extracellular and periplasmic Fe-precipitates
40nm-thick layer of iron minerals
Globules at the cellsurface
Extracellularmineralized filaments
Outer membrane
Plasmicmembrane
40nm
40nm-thick layer = Periplasmic encrustationColloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

3h 6h
1 day 3 days 6 days
2µm 2µm
1µm 2µm 2µm
Fe(II)Fe(III)
Temporal evolution of iron redox state (STXM)
Both bacteria AND extracellular precipitates are eventually oxidized!Miot et al. GCA 2009
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

0 0.2 0.4 0.6 0.8 1
Num
ber
of p
ixel
s
Fe(III)/Fe(total)
3 h
1 jour
3 jours
6 jours
0.18
0.28
0.27
0.39
0.80
0.50
0.94
0.55
50
Miot et al., Geobiology (2009)
Bacteria
Extracellularprecipitates
Iron gets oxidized on/in the cells
Quantitative evolution of iron redox vs. time
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

100 nm
200 nm
Cell encrustation vs. Time:Cryo-TEM on cryo-sections
Precipitation starts on the plasmic membraneThen extends and fills the entire periplasm
Fe-oxidation likely occurs within the periplasm
1
2
3
200 nm
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

ProteinsFe
Proteins are preserved in the encrusted periplasm
1 μm
Interesting for the one looking for fossils in old rocks
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Biomineralization of Fe by neutrophilic Fe-oxidizing bacteria
• Where is Fe(II) oxidized?→ probably within the periplasm. Sometimes outside the cells but…
• Where does Fe(III) precipitate?→ clearly within the periplasm then at the surface of the cells
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Is encrustation of BoFen1 cells lethal?
% of encrusted cellsvs. time
Number of viable cellsvs. time
Biomass vs. time
+Fe
No-Fe
+Fe
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

SW2 does not encrust
TEM SEM
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

0
C map Fe mapcell
filaments
Fe precipitates on extracellular filaments
1 μm
Miot et al. AEM 2009
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Fe-redox gradients along the filaments
1 µm
Fe(II)
500 nm
Fe(II)
cell
medium
0 0.5 1 1.50.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Fe(I
II)/
Fe t
otal
Distance, µm
cell medium
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

SW2
Adsorption
NucleationLimited growth
lipo-polysaccharidicfiber
Extracellular biomin
BoFeN1 Polysaccharidicfilament
Fossilization of proteinsBiomin in
periplasm
Nucleationlimited growth
Fe-biomineralization by neutrophilic Fe-oxidizing bacteria
Different patterns of biomineralization. Is there a genetic basis?
Extracellular biomin
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Bacterial biomineralization is not limited to Fe-minerals, AMD or modern Earth…
Stromatolitesmodern and fossil (up tp 3.5 Ga)
Banded Iron FormationPrecambrian (up to 3.8 Ga)
Pathogenic aortic calcification
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

→ Need for coupling mineralogy/geochemistry and (molecular) biology tools
Conclusions
What is the quantitative importance of bacterial biomineralization?
What do biominerals tell us about past environments?
Are there adaptations for/against biomineralization?
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009

Georges Ona-NguemaJennyfer MiotGuillaume MorinFrançois Guyot
Corinne CasiotOdile Bruneel
Anniet Laverman
François Farges
Gordon E. Brown, Jr
Andreas KapplerMartin Obst
Co-auteurs et remerciements
Institut de Minéralogie et de Physique des Milieux Condensés (IMPMC)
Paris
Hydrosciences Montpellier
Sisyphe, Paris
MNHN, Paris
University Stanford, USA
University Tuebingen, Germany
Colloque Minéralogie environnementale - Académie des sciences - 14-15 septembre 2009