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Microalgae:
the
first
nuclear
engineers?

the
past
10
years
we
have
shown
that
a
single
mutation
of
large
effect,
which
occur

previously
to
selective
agent
exposure
and
are
maintained
in
microalgae

populations
as
mutation-­-selection
balance
allow
adaptation
of
microalgae
to

pesticides
(18,
23-­-25),
xenobiotics
(26),
algaecides
(27-­-28),
mine
spills
(29-­-31)

volcanic
effluents
and
thermal
waters
(32-­-33).

4.
MICROALGAE
ARE
ABLE
TO
CONCENTRATE
URANIUM

Once
it
is
found
that
microalgae
can
survive
in
an
environment
with
large

amounts
of
Uranium
the
next
step
for
become
able
to
build
a
natural
nuclear

reactor
is
that
microalgae
can
to
concentrate
uranium.
However,
it
not
seems
easy

that
microalgae
could
concentrate
uranium
because
U
has
not
knowledge

biological
utility.
Consequently,
we
look
for
the
possibility
of
uranium
intracellular

and
extracellular
sequestration
in
the
Chlamydomonas
cells
collected
from
the

Saelices
evaporation
pond
(containing
25
mg
l-­-1
of
uranium).

An
Inductively
Coupled
Plasma-­-Mass
Spectrometry
(ICP-­-MS
VARIAN

RedTop)
analysis
demonstrated
that
Chlamydomonas
cells
bind
a
considerable

total
uranium
quantity
as
115
mg
U
g-­-1
of
dried
biomass.
Additionally,
ICP-­-MS
and

EDX
microanalysis
confirmed
the
participation
of
two
different
mechanisms
in
the

uranium
removal:
bio-­-adsorption
to
the
cell
wall
(and
bioaccumulation
within
the

cell
(Figure
4).

Figure
4.-­-
TEM
imagines,
a)
bio-­-adsorption
in
the
cells
wall,
b)
bio-­-accumulation
of
U
inside
the

cells
and
c)
TEM-­-XEDS
analysis,
in
Chlamydomonas
sp.
Arrow
detail
in
inlet
showing
uranium

precipitates.

5.

MICROALGAE
ARE
ABLE
TO
ENRICH
URANIUM
(PRODUCING
ISOTOPIC

FRACTIONATION
235U/238U).

In
all
probability
the
hardest
challenge
to
meet
is
that
microalgae
could
get

isotopic
fractionation
of
uranium.
However,
after
decades
of
study
of
stable

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