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.