Given
the
high
salinity,
prevailing
annual
high
temperatures,
and
ultra-oligotrophic
conditions
in
the
Red
Sea
isolation
and
characterization
of
important
microbial
groups
thriving
in
this
environment
is
important
in
understanding
the
ecological
significance
and
metabolic
capabilities
of
these
communities.
By
using
a
high-throughput
cultivation
technique
in
natural
seawater
amended
with
minute
amounts
of
nutrients,
members
of
the
rare
biosphere
(PS1),
methylotrophic
Betaproteobacteria
(OM43),
and
the
ubiquitous
and
abundant
SAR11
group
(Pelagibacterales),
were
isolated
in
pure
culture.
Phylogenetic
analyses
of
Red
Sea
isolates
along
with
comparative
genomics
with
close
representatives
from
disparate
provinces
revealed
ecotypes
and
genomic
differentiation
among
the
groups.
Firstly,
the
PS1
alphaproteobacterial
clade
was
found
to
be
present
in
very
low
abundance
in
several
metagenomic
datasets
form
divergent
environments.
While
strain
RS24
(Red
Sea)
harbored
genomic
islands
involved
in
polymer
degradation,
IMCC14465
(East
(Japan)
Sea)
contained
unique
genes
for
degradation
of
aromatic
compounds.
Secondly,
methylotrophic
OM43
bacteria
from
the
Red
Sea
(F5,
G12
and
H7)
showed
higher
similarities
with
KB13
isolate
from
Hawaii,
forming
a
‘H-RS’
(Hawaii-Red
Sea)
cluster
separate
from
HTCC2181
(Oregon
isolate).
HTCC2181
members
were
shown
to
prevail
in
cold,
productive
coastal
environments
and
had
an
nqrA-F
system
for
energy
generation
by
sodium
motive
force.
On
the
contrary,
H-RS
cluster
members
may
be
better
adapted
to
warm
and
oligotrophic
environments,
and
seem
to
generate
energy
by
using
a
proton-translocating
NADH:Quinone
oxidoreductase
(complex
I;
nuoA-N
subunits).
Moreover,
F5,
G12,
and
H7
had
unique
proteins
related
to
resistance
to
UV,
temperature
and
salinity,
in
addition
to
a
heavy
metal
‘resistance
island’
as
adaptive
traits
to
cope
with
the
environmental
conditions
in
the
Red
Sea.
Finally,
description
of
the
Red
Sea
Pelagibacterales
isolates
from
the
Ia
(RS39)
and
Ib
(RS40)
subgroups,
principally
revealed
unique
putative
systems
for
iron
uptake
and
myo-inositol
utilization
in
RS39,
and
a
potential
phosphonates
biosynthetic
pathway
present
in
RS40.
The
findings
presented
here
reflect
how
environments
influence
the
genomic
repertoire
of
microbial
communities
and
shows
novel
metabolisms
and
putative
pathways
as
unique
adaptive
qualities
in
diverse
microbes
encompassing
from
rare
to
predominant
bacterioplankton
groups
from
the
Red
Sea.
Date of Award | May 2015 |
---|
Original language | English (US) |
---|
Awarding Institution | - Biological, Environmental Sciences and Engineering
|
---|
Supervisor | Ulrich Stingl (Supervisor) |
---|
- Dilution-to-Extinction
- SAR11 clade
- OM43 clade
- PS1 clade
- Comparative Genomics
- Red Sea