Using Molecular Approaches to Describe Microbial Populations at Contaminated
Sites
By Sheridan K. Haack and Lisa A. Reynolds
ABSTRACT
Information about the distribution, numbers, types and activities of bacteria
and other microorganisms at contaminated sites is important for proper site
characterization, for selection of sampling sites, for development of monitoring
strategies and for development of accurate site models. The nucleic acids
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), extracted from sediments
at contaminated sites, can provide information on the identity, biomass and
biodegradative pathways of bacteria. This project employs several nucleic-acid
based methods to study bacterial community and population dynamics at a representative
site at which ground water is contaminated with fuel and chlorinated compounds.
Using these molecular methods, bacterial community composition and population
abundance at this site have been observed to vary spatially over scales of
less than 1 meter and temporally over scales of months. Changes in bacterial
communities and populations can be used to infer the reasons for spatial and
temporal changes in aqueous geochemistry and contaminant chemistry at this
site. Molecular methods provide information about bacterial biodegradative
processes at contaminated sites that cannot be obtained using traditional
microbiological methods.