Anammox
is
an
energy-efficient
nitrogen
removal
process
in
which
anammox
bacteria
(AnAOB)
oxidize
NH4+-N
to
N2
using
NO2--N
as
the
electron
acceptor.
Recent
evidence
suggests
that
AnAOB
can
perform
extracellular
transfer
(EET),
potentially
coupling
Fe(III)
reduction
with
oxidation
(Feammox).
However,
whether
directly
participate
Feammox
within
complex
wastewater
treatment
systems
remains
unclear.
Here,
we
investigated
iron-mediated
metabolism
pathways
a
microaerobic
granular
sludge
(MGS)
reactor
by
integrating
enzyme
inhibition
assays
analyses
of
gene
dynamics
and
co-occurrence
patterns
nitrogen-
iron-cycling
genes.
Results
demonstrate
contributed
activity.
The
iron
CT573071,
coding
porin-cytochrome
c
protein
associated
EET,
co-occurred
hao,
hzsABC,
hdh
genes
Candidatus
Kuenenia,
suggesting
its
role
Feammox.
Furthermore,
four
high-quality
metagenome-assembled
genomes
(MAGs)
affiliated
Kuenenia
stuttgartiensis_A
harbored
hao-like,
genes,
along
hao-cluster,
catalyzes
hydroxylamine.
This
genomic
further
supports
their
dual
metabolic
capacity.
Metatranscriptomic
analysis
confirmed
CT573071
upregulation
coexpression
These
findings
establish
potential
K.
Feammox,
providing
novel
insights
into
low-strength
systems.
