New Species Of Cyanobacteria Forms Intracellular Carbonates

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New Species of Cyanobacteria Forms Intracellular Carbonates
Publications about this research:
E.
Courafeau,
K.
Benzerara,
E. Gérard, D. Moreira, S. Bernard,
G.E. Brown Jr., and P. López-
A new species of cyanobac-
García, “An Early-Branching Micro-
teria—photosynthetic bacteria
bialite
Cyanobacterium
Forms
that occupy a wide array of
Intracellular Carbonates,” Science
habitats—was
discovered
in
336, 459 (2012). R.Riding, “A Hard
the Mexican Lake of Alchichica
Life for Cyanobacteria,” Science
where massive carbonate rocks
336, 427 (2012).
form. Cyanobacteria have been
Research
conducted
by:
impacting the global carbon
E. Courafeau, K. Benzerara, E.
cycle of the Earth for more
Gérard, D. Moreira and P. López-
than 2.3 billion years by assim-
García
(CNRS,
France),
S.
ilating CO
into organic com-
Bernard, G.E. Brown Jr. (Stanford
2
pounds and triggering calcium
University and SLAC National
carbonate (CaCO
) precipitation.
Accelerator Laboratory).
3
Despite the importance of this
Research funding: CNRS interdis-
cyanobacteria-mediated CaCO
3
ciplinary program “Environnements
biomineralization, the mecha-
Scanning electron microscopy image of two intracellularly
planétaires et origines de la vie”
nistic details of this process
calcifying cyanobacterial cells. Ca-, Mg-, Sr- and Ba-carbonate
and Institut National des Sciences
inclusions appear as bright spheres. Cells are deposited on a filter
are still poorly understood.
de
l’Univers
(INSU)
program
with 200-nm wide pores. Scale bar is 1 micron.
Scientists agree that calcifica-
“InteractionsTerre/Vie.” Operation
tion
in
cyanobacteria
is
of the ALS is supported by the U.S.
an
extracellular
process:
Department of Energy, Office of
Photosynthesizing cells com-
means
glutinous,
margarita
eV), the STXM provided key
Basic Energy Sciences.
monly export the photosynthe-
means pearl, and lithophora
chemical speciation–sensitive
sis byproduct CO3
outside
means “bearing stones”). The
images at a spatial resolution
2-
their cells where it bonds
team of scientists that discov-
better than 25 nm. The soft
with an alkaline earth metal
ered this species found that
x-ray STXM enabled character-
like Ca
. The cyanobacteria
mineral inclusions can com-
ization
of
the
type
(i.e.,
2+
recently
found
in
Lake
pose up to 6% of the total cell
coordination and/or reduction-
Alchichica,
however,
forms
volume
of
Gm.
lithophora,
oxidation
state)
of
carbon
amorphous Ca-, Mg-, Sr- and
increasing
cell
density
by
composing
the
cells,
the
Ba-rich carbonates intracellu-
approximately 12%. This extra
carbonates’ inclusions could be
larly. This discovery signifi-
weight may help to weigh
identified based on XANES
cantly modifies the traditional
down
the
microorganisms,
spectroscopy at the C K-edge,
view of how bacteria induce
which live on rock substrates.
and the speciation of calcium
CaCO
precipitation and may
Researchers performed a
was based on the Ca L
-edges.
3
2,3
improve
understanding
of
combination of microscopies,
Surprisingly,
intracellular
vs. Mg
(CO
)
(OH)
4(H
O) or
5
3
4
2•
2
the fossil record by hinting
including soft x-ray scanning
inclusions
formed
by
Gm.
CaCO
for extracellular well-
3
at ancient traces of life in
transmission x-ray microscopy
lithophora are amorphous by
crystallized
minerals.
This
rocks, or designing new routes
(STXM), on ALS Beamlines
electron diffraction and have
intracellular chemistry repre-
for sequestering CO
or
Sr
11.0.2
and
5.3.2.
When
a very different stoichiometry
sents a 90-fold and 1370-fold
90
2
in minerals.
coupled with x-ray absorption
from the minerals forming
increase, respectively, in inclu-
The new species of cyano-
near edge spectra (XANES)
outside the cells: for example,
sion Sr/Ca and Ba/Ca ratios
bacteria is named Candidatus
over
a
relatively
extended
(Sr
Ba
Mg
Ca
Ca
Mg(CO
)
as compared to the extracellular
1
2.7
1.4
0.9
6
3
13
Gloeomargarita lithophora (gloeo
range of energies (100–2000
for
intracellular
inclusions
solution, suggesting the existence

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