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Metagenomic Analysis of Water Distribution System Bacterial Communities
Citation:
REVETTA, R. P. AND J. W. SANTO-DOMINGO. Metagenomic Analysis of Water Distribution System Bacterial Communities. Presented at 2008 USEPA SCIENCE FORUM, WASHINGTON, DC, May 19 - 21, 2008.
Impact/Purpose:
to present information
Description:
The microbial quality of drinking water is assessed using culture-based methods that are highly selective and that tend to underestimate the densities and diversity of microbial populations inhabiting distribution systems. In order to better understand the effect of different disinfection treatments on the bacteria in water distribution systems (WDS) we have recently developed and analyzed 16S rRNA gene clone libraries using DNA and RNA extracted from samples collected at different times and locations in a metropolitan distribution system. Phylogenetic analyses and sequence comparisons with existing databases reveal that alpha- and beta-Proteobacteria are predominant bacterial groups in both biofilm and planktonic communities. Sequence analysis of RNA-based clones suggest that the active bacterial fraction consisted of fewer dominant bacterial groups, including Nevskia ramosa, a member of the gamma-Proteobacteria group. Some of the bacterial groups identified in our clone libraries are affiliated with yet to be cultured organisms suggesting that a significant fraction of drinking water communities cannot be studied using culturing methods. The results from these studies suggest that we have a limited understanding of the molecular diversity and population dynamics of WDS microbial communities. As conventional 16S rDNA-based cloning techniques are prone to PCR biases and only provide limited information on in situ microbial function, future studies will focus on the developing and analyzing metagenomic sequencing databases. The benefits of using metagenomics to more accurately characterize the microbial functional diversity of drinking water systems and better understand functional microbial networks will be discussed.