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ASSESSMENT OF FECAL POLLUTION SOURCES IN PLUM CREEK WATERSHED USING BACTEROIDETES 16S RDNA-BASED ASSAYS
Citation:
LAMENDELLA, R., J. W. SANTO-DOMINGO, D. B. OERTHER, J. VOGEL, AND D. STOECKEL. ASSESSMENT OF FECAL POLLUTION SOURCES IN PLUM CREEK WATERSHED USING BACTEROIDETES 16S RDNA-BASED ASSAYS. Presented at 2006 American Society for Microbiology Annual Meeting, Orlando, FL, May 22 - 25, 2006.
Impact/Purpose:
To inform the public
Description:
Recently, 16S rDNA Bacteroidetes-targeted PCR assays were developed to discriminate between ruminant and human fecal pollution. These assays are rapid and relatively inexpensive but have been used in a limited number of studies. In this study, we evaluated the efficacy of human and ruminant-specific 16S rDNA Bacteroidetes assays in determining the primary sources of fecal pollution in Plum Creek (NE) watershed. The sensitivity and specificity, as well as the temporal and spatial application of these assays were challenged against feces from different animals, water, and sediment samples from this watershed. Phylogenetic analyses of 981 fecal and environmental 16S rDNA clones were also performed to study the diversity of Bacteroidetes in this watershed. On average, the host specific assays indicated that ruminant feces were present in more than one-third of the water samples and in all sampling seasons, with increasing frequency in downstream sites along Plum Creek. The human-targeted assay indicated that only 5% of the water samples were positive for human fecal signals, although a higher percentage of human-associated signals (24%) were detected in sediment samples. Phylogenetic analysis of Bacteroidetes 16S rDNA sequences derived from fecal and environmental samples demonstrated the presence of a high level of sequence diversity, with nearly half of the recovered sequences showing less than 97% identity to sequences found in publicly available databases. Approximately, 60% of all clones clustered with yet to be cultured Bacteroidetes species associated with sequences obtained from ruminant feces, further supporting the prevalence of ruminant contamination in this watershed. The sequencing data also indicated that other sources, including humans, sediments, and wildlife may be significantly contributing to the molecular diversity of fecal Bacteroidetes in this watershed. Since several clusters contained sequences from multiple sources, future studies must take into consideration the potential cosmopolitan nature of bacterial populations when assessing fecal pollution sources using Bacteroidetes markers.