Fluorescence In-Situ Hybridizations (FISH) are being coupled with more
traditional groundwater monitoring techniques to evaluate a coal-tar
impacted aquifer in Northwestern Iowa for intrinsic bioremediation potential.
FISH is a molecular method that allows semi-quantitative identification
of specific microorganisms without cultivation. It is the process of
binding (hybridizing) a small oligonucleotide probe containing a reporter
molecule to complimentary cellular rRNA in target cells. rRNA is an
ideal target because it contains both highly conserved and highly variable
regions of genetic coding. When visualized under a microscope, microbes
in complex environmental samples can be identified and enumerated. This
lends to the ability to infer the occurrance of specific microbial processes
based on differences in microbial structure associated with specific
system perturbations. In the case of the coal-tar impacted aquifer.
we are specifically looking for an increase of gross microbes associated
with the contaminant plume, changes in groundwater redox chemistry that
would be consistent to microbially-induced oxidation-reduction reactions,
decreasing contaminant concentrations with time at individual sampling
locations, and the enrichment in specific taxa that are known to harbor
PAH-degrading microorganisms. We are probing the aquifer soils with
oligos specific to the taxa shown in yellow. The stars denote taxa which
harbor known PAH-degrading organisms, and are of particular interest.