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& Staff > Dr. Tim McDermott
Microbial Distribution and Activities in Acid Sulfate Chloride Springs in
Yellowstone National Park
The McDermott laboratory currently focuses most of its efforts on a low pH
geothermal feature known as Dragon Spring located in Norris Geyser Basin, Yellowstone
National Park. This spring has source water temperatures ranging from
68-73°C and a pH of 2.9-3.1. The source water contains high concentrations
of CO2 (~ 4 mM), and several reduced chemical species that
could serve as energy sources and include: As(III), Fe(II),
H2S, and H2. Elemental
sulfur is also present in great abundance and can be used as an electron donor
or acceptor. Our past efforts have involved molecular surveys to characterize
the microbial community structure and geochemical analyses that have identified
major geochemical inputs and microbial transformation products. Current
efforts strive to link specific populations with biogeochemical activities
in order to understand the functional contributions of the different populations. For
this we currently use: cultivation work to obtain ecologically relevant organisms
for in vitro modeling exercises; quantitative PCR to understand population
distribution patterns; reverse transcriptase PCR to examine expression of specific
functional genes; and expression arrays to probe the community transcriptome
of well defined regions of the spring. All of these efforts are combined
with geochemical analyses of solutes and gases, and that strive to link specific
populations with specific functions.
 Chemolithotrophy. One of our research thrusts studies
chemolithoautotrophic prokaryotic populations and their activities that contribute
to biogeochemical cycling and biomineralization. These efforts focus
on the yellow S0 deposition
area, which comprises the first well-defined geochemical zone as the water discharges
from the spring source. This region of the spring is characterized by decreasing
gradients of temperature, overlapping H2S, and H2, and
is home to approximately nine populations of Hydrogenobaculum that occur
primarily in the center of the flow channel. These organisms utilize both
H2S and H2 as energy
sources, and O2 or NO3- as electron acceptors,
and their H2S oxidation contributes significantly to the accumulation
of S0 in
this region of the spring. Other organisms of interest include two Acidicauldus populations
that occur where the S0 zone transitions to the brown iron phase. These
organisms utilize As(III) as an energy source.
Cyanidia Ecology. At lower temperatures (38-48°C), cyanidia often
dominate the biomass of acidic geothermal springs. Surprisingly little
is known about these intriguing organisms, and so our efforts are designed
to learn more about these algae and their overall contribution(s) to community
function. Initial studies have investigated population diversity and
dynamics, generating considerable evidence that suggests there are numerous
distinct populations within a single well-defined region and that their numbers
are extremely dynamic. The latter appears to be linked with temperature
and UV light exposure. Interestingly, our studies also indicate that
these algae make significant contributions to arsenic transformations in these
springs.
Thermal soil at Fairy Falls
 Underground
geothermal
expansion event resulting in tree death
 Norris
Geyser Basin, December 2003.
Air temperature
= -25° F
 Norris
Geyser Basin,
July 2003
 Sampling
at Dragon Spring
 Dragon
Spring,
Robust arsenite oxidizing community
Current Laboratory Personnel:
Dr. Des Kashyap, Postdoctoral Associate
Dr. Corrine Lehr, Postdoctoral Associate
Seth D'Imperio, Ph.D. Student
Lisa Kirk, PhD Student
Dana Skorupa, Ph.D. Student
Shaun Frank, Undergraduate Student
Alex Kalinin, Undergraduate Student
The McDermott research group
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