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Molecular diversity of drinking water bacterial communities using 16S rRNA gene sequence analyses
Citation:
Humringhouse, B., R. Revetta, D. Oerther, AND J. W. SANTO-DOMINGO. Molecular diversity of drinking water bacterial communities using 16S rRNA gene sequence analyses . Presented at Water Quality Technology Conference and Exposition, Cincinnati, OH, November 16 - 20, 2008.
Impact/Purpose:
To share information
Description:
Our understanding of the microbial community structure of drinking water distribution system has relied on culture-based methods. However, recent studies have suggested that the majority of bacteria inhabiting distribution systems are unable to grow on artificial media. The goal of this study was to improve our understanding of such microbial network using sequence analysis of the 16S rRNA gene. Total DNA was extracted from bulk phase water from over 20 sampling sites within a metropolitan distribution system during a 12 months period. DNA extracts were then used to develop 16S rRNA gene clone libraries. A total of 2400 16S rDNA clones were analyzed in this study. Using existing databases for sequence comparison, 70% of the clones analyzed showed at least 97% sequence identity with sequences in current databases. The most predominant bacterial groups were closely related to a-Proteobacteria and Mycobacterium sp., representing nearly 40% and 36% of the total clones examined, respectively. Clones related to Shingomonas spp. and M. gordonae were common among the a-Proteobacteria and Mycobacterium clades, respectively, but in each clade sequences related to uncultured bacteria were highly represented. Sequences similar to ί-Proteobacteria (e.g., Dechloromonas), γ-Proteobacteria (e.g., Legionella), Firmicutes (e.g., Lactobacillus spp), and Bacteroidetes (Flavobacterium spp.) were also identified, but represented a smaller fraction of the community. Using 97% as the operational taxonomic unit, rarefaction analysis and diversity indices suggested that more clones should be examined in order to have a more accurate representation of the diversity of inhabiting bacterial populations. As a considerable number of the clones are closely related to uncultured bacteria, these results further suggest the need for culture independent methods to study the microbial dynamics of drinking water distribution systems.