Phylogeny and Biogeochemistry for the Discovery of Novel Chemolithotrophs
Gradients in Yellowstone National Park
Norris Geyser Basin in Yellowstone National Park represents
one of the most diverse geochemical environments on Earth, and
the perfect venue for a comprehensive research thrust aimed at
discovering novel chemolithotrophic microorganisms. In terms of
described general physiological groups, chemolithotrophs are tremendously
underrepresented - particularly given the predominance of inorganic
energy sources in our biosphere. Our microbial observatory is
located in Hundred Springs Plain, Norris Geyser Basin, a dynamic
geothermal complex comprised of hundreds of thermal acid-sulfate-chloride
springs that vary significantly with respect to inorganic constituents
and temperature – both are significant environmental selectors
that occur in numerous gradients in these springs.
These springs contain high concentrations of Fe2+, S0, H2, H2S,
and As(III) which represent the predominant potential electron
donors driving nonphotosynthetic primary production. Our research
utilizes novel cultivation and molecular techniques to describe,
characterize, and isolate the microbial populations present along
geochemical and temperature gradients. This detailed description
of the microbiology is accompanied by a complete analysis of the
aqueous and solid phase geochemistry associated with these communities
and that no doubt select for, and define, the populations inhabiting
these inorganic environments.
Our specific objectives are:
Objective 1: Characterize aqueous and surface chemical
processes associated with S, Fe and As cycling in acid-sulfate-chloride
thermal springs, emphasizing the nature of chemical gradients
and microenvironmental conditions that define the ecological context
of native microbial populations.
Objective 2: Employ culture-independent techniques, including
a novel PCR approach, to describe native microbial populations,
examine community dynamics, and to correlate community composition
with the geochemical perspectives derived from Objective 1.
Objective 3: Apply more realistic cultivation approaches that
account for key environmental factors and that utilize surfaces
and flow-through systems to isolate previously uncultured microorganisms
or whole communities involved in chemolithotrophic metabolism.
In addition to offering significant promise for discovery of
previously unknown microorganisms, our studies contribute significantly
to the general development of microbial ecology principles. Our
comprehensive, multidisciplinary approach links molecular description
with the more difficult task of understanding the relevance of
specific microbial populations in their natural environments and
the patterns in microbial ecology that reflect the environmental
context of specific phylogeny.