Redox
cycling
of
iron
plays
a
pivotal
role
in
both
nutrient
acquisition
by
living
organisms
and
the
geochemical
elements
aquatic
environments.
In
nature,
is
mediated
microbial
Fe(II)-oxidizers
Fe(III)-reducers
or
through
interplay
biotic
abiotic
transformation
processes.
Here,
we
unveil
specific
process
driven
one
single
phototrophic
species,
Rhodobacter
ferrooxidans
SW2.
It
exhibits
capability
to
reduce
Fe(III)
during
bacterial
cultivation.
A
c
-type
cytochrome
identified
with
Fe(III)-reducing
activity,
implying
linkage
reduction
electron
transport
system.
R.
SW2
can
mediate
redox
transformation,
depending
on
availability
light
and/or
organic
substrates.
Iron
anoxygenic
photoferrotrophs
proposed
exist
worldwide
modern
ancient
Our
work
not
only
enriches
theoretical
basis
nature
but
also
implies
multiple
roles
Microbial
carbon
(C)
use
efficiency
(CUE)
drives
soil
C
formation,
while
physical-chemical
protection
stabilizes
subsequent
microbial
necromass,
both
shaped
by
aggregates
and
minerals.
Soils
inherit
many
properties
from
the
parent
material,
yet
influence
of
lithology
associated
geochemistry
on
CUE
necromass
stabilization
remains
unknow.
Here,
we
quantified
in
well-aggregated
bulk
soils
crushed
aggregates,
as
well
mineral-associated
organic
matter
fraction,
originating
carbonate-containing
(karst)
carbonate-free
(clastic
rock,
nonkarst)
materials
along
a
broad
climatic
gradient.
We
found
that
aggregate
crushing
significantly
increased
karst
nonkarst
soils.
Additionally,
compared
to
soils,
calcium-rich
macroaggregate
stability
decreased
ratio
oligotrophic
copiotrophic
taxa,
leading
reduction
CUE.
Moreover,
was
negatively
with
iron
(hydr)oxides
attributed
greater
abundance
higher
pH.
Despite
negative
effects
aggregation
minerals
CUE,
particularly
these
concurrently
showed
through
organo-mineral
associations
Consequently,
(i)
bedrock
mediates
stability;
(ii)
balancing
minerals'
dual
roles
diminishing
enhancing
is
vital
for
optimizing
preservation.
Carbonaceous
materials,
including
activated
carbon
and
pyrolytic
carbon,
have
been
recognized
for
about
over
a
decade
as
effective
electron
shuttles
or
conductive
materials
in
promoting
microbial
Fe(III)
mineral
reduction.
However,
recent
studies
reveal
inhibitory
effects,
sparking
debates
their
overall
impact.
We
hypothesized
that
the
physical
contact
between
bacteria
is
an
overlooked
yet
critical
factor
determining
whether
promotes
inhibits
Using
systems
containing
Shewanella
oneidensis
MR-1,
ferrihydrite,
we
investigated
how
carbon-iron
oxide
aggregate
structure
affects
reduction
kinetics.
At
low
carbon-to-iron
ratios
(C/Fe
=
5:7
by
mass),
ferrihydrite
aggregated
with
forming
carbon-encapsulated
particles
suppressed
rates.
Conversely,
at
higher
100:7),
dispersed
on
surface,
enhancing
both
rate
extent
of
Tests
11
different
carbonaceous
(activated
biochar)
all
confirmed
microstructure
iron
oxides─whether
encapsulating
dispersed─on
surfaces
This
insight
resolves
debate
promote
inhibit
enhances
our
understanding
roles
biogeochemical
processes
environmental
remediation.
Environmental Science & Technology,
Journal Year:
2024,
Volume and Issue:
58(41), P. 18222 - 18233
Published: Oct. 1, 2024
Soil
contamination
by
multiple
metals
is
a
significant
concern
due
to
the
interlinked
mobilization
processes.
The
challenges
in
comprehending
this
issue
arise
from
poorly
characterized
interaction
among
different
and
complexities
introduced
spatial
temporal
heterogeneity
soil
systems.
We
delved
into
these
incubating
size-fractionated
paddy
soils
under
both
anaerobic
aerobic
conditions,
utilizing
combination
of
techniques
for
aqueous
colloidal
analysis.
contaminated
predominantly
consisted
particles
measuring
<53,
250-53,
2000-250
μm,
with
<53
μm
fractions
exhibiting
highest
concentrations
metals.
Interestingly,
despite
their
higher
overall
content,
released
less
dissolved
metal.
Furthermore,
glucose
enhanced
release
arsenic
while
simultaneously
promoting
sequestration
other
metals,
such
as
Pb,
Zn,
Cu.
Utilizing
asymmetric
flow
field-flow
fractionation,
we
unveiled
presence
fine
(0.3-130
kDa)
large
(130-450
nm)
pools,
each
carrying
various
affinities
iron
minerals
organic
matter.
Our
results
highlighted
pivotal
role
fraction
reservoir
metal
contaminants
soils,
which
were
mainly
associated
These
findings
illuminated
size-resolved
dynamics
cycling
provided
insights
developing
remediation
strategies
metal-contaminated
ecosystems.
Biochar
has
great
potential
in
reducing
the
abundance
of
antibiotic
resistance
genes
(ARGs)
and
mobile
genetic
elements
(MGEs)
from
soil.
However,
its
efficiency
removing
other
biological
pollutants,
such
as
human
bacterial
pathogens
(HBPs)
virulence
factor
(VFGs),
is
rarely
studied.
Herein,
by
pyrolyzing
rice
straw
(RS)
pine
wood
(PW)
at
350
700
°C,
we
prepared
a
series
biochar
(RS350,
RS700,
PW350,
PW700)
investigated
their
impacts
on
pathogenicity
HBPs.
Compared
with
PW
biochar,
RS
effectively
reduced
HBPs
6.3-40.1%,
well
pathogenicity,
evidenced
an
8.2-10.1%
reduction
VFGs.
Mechanistically,
more
persistent
free
radicals
(PFRs)
were
formed
than
that
during
pyrolysis,
PFRs
triggered
degradation
