2. Community responses to pollutant stresses
A number of projects regarding bioremediation have been conducted in the CME project laboratory. Our work on a chromium contaminated superfund site is a comprehensive look into the structure of microbial communities in the diverse soil geochemistries found across the 75-acre study site. A total of 90 microbial communities have been dissected with 16S rRNA T-RFLP, PLFA and DGGE analyses. A collaboration with Oak Ridge National Labs will help to analyze the community data along with the extensive geochemistry on metal concentrations, organic carbon, and soil types. An extensive collection of Cr resistant heterotrophs has been isolated. Multiple metal resistance patterns have been determined and the phylogeny of selected representatives has been determined by sequencing 16S rRNAs (manuscript in preparation). A detailed study of the microbial communities at four sub-sites and three depths using specific primers for both the Archaeal and Bacterial domains as well as a group specific primer set for the Bacteroides-Cytophaga-Flexibacter (BCF) group has been completed. This study will include a 16S rRNA sequence analysis of phylogenetic diversity within the BCF group (manuscript in preparation). An extensive series of microcosm experiments conducted to evaluate the extent of Cr leaching from soils under conditions designed to simulate natural events has been concluded and will be reported on shortly. We are also involved in microbial community analyses of contaminated (Bachmann) and uncontaminated (South Oyster) aquifers in an effort to more completely understand the response of aquifer communities to toxic challenge. These studies include T-RFLP analyses of the bacterial community as well as direct phylogenetic analyses. In addition we are planning to measure the time required to re-colonization aquifer sediment after dramatic changes brought about by high levels of pollutants. This past summer we have concluded microbial community analyses on the Dover AFB plume currently undergoing intrinsic bioremediation (RTDF Funding). These data are being analyzed and compared with the extensive geochemistry of the site to identify correlations and trends.
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