Download Microorganisms and Climate Change

How are micro-communites adapting?
Microorganisms
and Climate
Change
he Earth’s climate is
changing. It is not the
first time it has
changed, and it is unlikely
that it will be the last.
T
By Rianna Malherbe,
MS, RM (NRCM)
Rianna Malherbe is an R&D
Microbiologist and Technical
Support Specialist at Hardy
Diagnostics.
She earned her Bachelor’s and
Master’s Degrees at Cal Poly State
University, San Luis Obispo. Her
studies were focused on molecular
microbiology and genetics.
When she is not assisting
customers at Hardy Diagnostics,
she can be found hiking the hills of
San Luis Obispo County with her
husband, Ryan, and dog, Charlie.
Hardy Diagnostics
Earth had a very unstable
climate in the beginning –
starting out very warm and
undergoing extreme
fluctuations in temperature
and atmospheric content until
the Pleistocene Epoch about
2.7 million years ago. During
this time, it is estimated that
there were between 25-30 ice
ages with periods of warming
between them. During the
Holocene Epoch, after the last
ice age ended, it warmed to
the climate we know today.
Just in the last hundred years,
the Environmental Protection
Agency (EPA) estimates that
the Earth’s average
temperature has risen by
1.4°F. The agency expects the
temperature to rise another 2 11.5°F over the next hundred
years. As we have seen this
past year, the “hot” seasons
(think of the drought on the
West coast of the U.S.) have
gotten hotter and drier, and
the “cold” seasons (think of
Polar Vortex in the Mid-West
of the U.S.) have gotten
colder.
Regardless of how fast or why
the climate is changing, the
fact that it is changing should
be enough to consider how it
will affect the future. We may
not be able to stop climate
change, but we should
probably be prepared for it.
The circle of life we know
today is specific to the current
climate. Very generally,
plants use water and nutrients
from the soil and sunlight to
grow, animals eat the plants
(or they eat other animals that
eat plants), and
microorganisms decompose
dead plants and animals,
which replenish the nutrients
in soil. If any part of this
cycle is affected, the others
will likely suffer as well
through a domino effect.
A good example on the
macro-scale of possible
effects on the ecosystem is the
absence and re-introduction of
wolves in Yellowstone
National Park. In the early
20th century, wolves were
considered a nuisance as they
impacted livestock herds, so
their extermination was
encouraged.
However, the absence of
wolves soon allowed the deer
population to sky-rocket,
which reduced vegetation and
resulted in soil erosion. When
wolves were re-introduced,
the deer population was
reduced to a more sustainable
population, vegetation was
restored, and erosion became
less imminent, essentially
bringing the ecosystem back
into balance.
Endothermic organisms
(mainly, mammals) are
designed to cope with a few
degrees change in the
environment, because their
bodies work to regulate their
internal temperature.
However, exothermic
organisms (many plants,
invertebrates, and
microorganism communities)
cannot cope with rapid change
because they lack the time
needed to adapt and their
metabolism is more acutely
affected by the temperature
and humidity of their
environment.
Those of you with gardens in
the Western part of the U.S.
(myself included) may have
noticed that your plants were
not happy this past summer;
they just couldn’t get enough
water. And these are plants
that are irrigated!
Recently, there have been
studies that show that
microorganisms live in
communities similar to larger
ecosystems. These microcommunities may not only
live symbiotically with each
other but may be interdependent upon each other for
their survival. Each organism
may use byproducts of
neighboring organisms that, in
turn, produce byproducts for
other neighboring organisms.
Microorganisms have always
been useful to scientific
research because of their
acute reactions to
experimental conditions and
rapid generation time. Many
species require specific
temperatures and atmospheric
conditions for optimal growth.
When present in communities,
it is more difficult to
determine specific changes in
metabolism. Instead, the
composition of species in the
community is the best
indicator of health and
stability. There are many soil
scientists and microbiologists
studying how environmental
micro-changes affect
microorganism metabolism
and community interactions.
In dry areas such as the
southwestern U. S., these
micro-communities are called
Biological Soil Crusts. One of
the main organisms present in
these crusts is Cyanobacteria.
Cyanobacteria have
filamentous growth that
produces sticky
polysaccharide sheaths around
their cells to aid in soil
stability. They also bind
particles with rhizines and
rhizoids, which are root-like
structures of lichens and
mosses, respectively, that are
used for attachment. This
binding increases the
resistance to wind and water
erosion.
Ferran Garcia-Pichel’s lab at
the Arizona State University
is one group studying the
effects environmental changes
have on micro-communities in
these Biological Soil Crusts.
They predict that as
temperatures rise, plants,
animals and microorganisms
will need to move their range
to find their temperature
niche. In areas that have an
average increase in
temperature, heat-loving
species may begin to take
over. This will likely affect
the species composition of
micro-communities and open
niches for species with
different growth requirements
to replace them.
However, it is unknown how
much the microbial make-up
of soil crusts will change with
rapid weather changes.
Warmer temperatures could
mean more Cyanobacteria, a
different species of
Cyanobacteria, or a different
genus all together. Dr. GarciaPichel found that the species
of Cyanobacteria present in a
biological soil crust was
different depending upon the
geographic location of the
crust. Microcoeus vaginatus, a
type of cyanobacteria, was the
dominant species in soil crusts
found in cold places, like the
Colorado Plateau, wile M.
steenstruppii was dominant in
warm areas like the Sonoran
desert.
Laboratory experiments found
that when temperatures
differed, the microbes that
prevailed in their mini-testecosystem changed. The
temperature differences that
were tested were within the
EPA predicted temperature
changes over the next century,
so it’s presumed a similar
reaction would occur in wild
populations.
It is unknown if a changing
microbial composition will
matter – it is possible that a
similar replacement organism
may result in no net change in
input, productivity, or output.
Potentially, only variation in
genetic composition will
change. However, it is also
possible that the new
organism will not be as
drought tolerant, may result in
lower soil fertility, or will not
hold the soil together as well.
These traits could mean fewer
nutrients in vegetation for
grazing animals or faster or
more drastic erosion.
Yet another possibility is that
a different set of organisms
will be better at all of those
things than the current microcommunities or that new
species could also bring about
genetic changes in
pathogenicity that we have yet
to experience.
At this point, it is too early to
tell how ecosystems will
change, because it is largely
dependent on which
organisms are already present.
Every possibility could have
pros and cons, but should we
wait to find out?
Rianna Malherbe,
MS, RM(NRCM)
Santa Maria, California