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Biologists have found
a special bacterium in
Svalbard's wetlands
that gobbles up the
worst greenhouse gas
of them all: methane
To say that
Methylobakter tundripaludum
consumes methane is a little bit of an
understatement. These bacteria live in
the top layer of Svalbard's wetland soils
and filter the methane gas that is formed
in the soil and released from permafrost
when it melts.
"A bacterium is a simple, single-cell
organism, but it's also a small factory.
This bacteria uses methane to build new
cell material and to produce energy. The
rest is converted into CO
2
," says bio-
logy professor Mette Svenning. Areas
underlain by permafrost are a storehouse
of organic carbon – 50 per cent of the
Earth's carbon is stored here, in just 20
per cent of the Earth's land area.
"Because the permafrost is at a low tem-
perature and the season when bacterial
flora can be active is short, the turnover
of plants and animals is very slow. This
means that organic material such as dead
plant matter is broken down very slowly
via anaerobic bacterial processes. This is
the source of the methane production,"
says Svenning.
If the climate warms and the permafrost
thaws, this process will be reinforced and
the carbon will be released in the form of
methane (CH
4
), which is a greenhouse
gas that is 20 times more potent than
CO
2
.
Adapted to the Arctic
Bacteria that feed on methane are also
found in landfills, in rice paddies and
in soil. But
Methylobakter tundripalu-
dum
appears to be particularly suited
to Arctic conditions. This bacterium is
also found in some places in Siberia and
Alaska.
"Some may argue that Svalbard is not
representative of the Arctic environment
because it is an isolated archipelago. But
these bacteria are also found elsewhere
in the Arctic, which shows that what
happens in Svalbard enables us to draw
conclusions about much larger areas,"
Svenning says.
Now
Methylobakter tundripaludum
is
being analysed at the Joint Genome
Institute in the USA to sequence its
genes. This will enable it to be compared
to other bacteria and will also supply
more information about the Arctic orga-
nism itself.
"This may help to identify features that
we are not aware of yet. We know it has
a function in nature and that it is very
active in this ecosystem. But it belongs
to an ecosystem that we basically do not
know much about, so sequencing the
genes may reveal some secrets to us,"
Svenning says.
Can these bacteria help to reduce methane
emissions that result from global war-
ming?
"The bacteria live in extreme conditions,
and can withstand harsh environ
mental changes. For example, the opti-
mal temperature for this bacterium is
23° C. This means that they grow best
and are most active between 20 and 30
degrees. But the bacteria also grow even
if the temperature drops to 0 degrees. If
it continues to warm, then the perma-
frost will continue to thaw and methane
production will increase significantly. It
is possible to speculate that the con-
sumption of methane will also increase if
these bacteria become more active due to
higher temperatures," says Svenning.
"On the other hand: If the warming
thaws the permafrost and rainfall increa-
ses, there may be higher water levels in
wetlands. That would result in a situation
that would be much worse for these
bacteria because they require air, they
are aerobic. If they are drowned, this will
result in anaerobic conditions where they
cannot function as they should. That
means more methane will released to the
atmosphere."
Mapping microbial communities
It is not easy to understand all of the
relationships in complex ecosystems,
especially when you do not even have
an overview of the role that the smallest
organisms play. There are many micro-
organisms that have yet to be discovered,
or whose function in the community is
still unknown.
Bacteria
that eat greenhouse gases
20
•••
Labyrint E/11
– University of Tromsø
Here's what it looks like: Metylobakter tundripaludum. Photo: Mette Svenning