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Field and Simulated Conceptual Model
By the final two years of this project, we expect
that the computational group will have developed a conceptual model
of stress regulatory pathways. These models will be tested by subjecting
various reactor systems to various stress and recovery scenarios
and will be analyzed with the parameter presented in Subsection
2.4.4 of the proposal. We also anticipate that we will have
developed a number of new molecular probes that we can use to verify
the responses and pathways being used for various stressors. Once
we have validated these conceptual models in our controlled laboratory
simulations, we will use the same probes to validate these conceptual
models in the field. The field tests will use the same techniques
described for the original survey and mapping studies with the
addition of the newly developed stressor pathway molecular probes.
Field tests will involve push-pull tests similar to those already
performed at the NABIR FRC, along defined stressor gradients (25).
Depending on the stressor being tested amendments in the form of
electron donors, electron acceptors, nutrients, etc., may be added
to the environment to measure the expected stressor change. These
field tests will be developed in detail in consideration of the
test site, e.g., in association with the NABIR FRC Manager. Once
the conceptual models have been developed, a number of other field
tests might also be considered at other DOE sites. Questions to
then ask could include: (1) are Desulfovibrio-like, Shewanella-like,
and Geobacter-like organisms found at other contaminated sites;
(2) are the metabolites, genes, and pathways present at most sites;
(3) is there a direct correlation between the presence of certain
genes and pathways at sites with certain types and concentrations
of contaminants; and (4) can we induce particular stress responses
that might favor a desired outcome for contaminants in the subsurface
at some sites.
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