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PHYLOGENETIC ANALYSIS OF PROKARYOTIC AND EUKARYOTIC MICROORGANISMS IN A DRINKING WATER PIPE LOOP SYSTEM
Citation:
Williams, M M., M C. Meckes*, C A. Kelty*, J W. Santo Domingo*, AND H. Rochon. PHYLOGENETIC ANALYSIS OF PROKARYOTIC AND EUKARYOTIC MICROORGANISMS IN A DRINKING WATER PIPE LOOP SYSTEM. Presented at American Society for Microbiology General Meeting, Washington, DC, 05/18-22/2003.
Description:
Within potable water distribution systems, opportunistic pathogens such as Legionella species infect protozoa, gaining protection from disinfectant residuals. Analyzing the prokaryotic and eukaryotic populations in distribution system water provides a basis for understanding the interactions between these microorganisms. The objective of this study was to determine the phylogenetic affiliation of the prokaryotic and eukaryotic populations inhabiting a distribution system simulator. Samples were obtained from the feed and discharge water of a ductile iron pipe loop system receiving drinking water containing a 0.5 ppm monochloramine (NH2Cl) residual. Bacteria were isolated on R2A agar, then identified by sequence analysis of the 16S rRNA gene (rDNA). To determine a broader range of microbial populations present in the systems, clone libraries of 16S rDNA and 18S rDNA (i.e., specific to eukaryotic microorganisms) were made from sample water. The majority of the isolates were closely related to bacteria belonging to the alpha proteobacteria, including Sphingomonas, Brevundimonas, and Caulobacter species. Sequence analysis of the clones obtained from the pipe loop discharge water showed a mixture of alpha and beta proteobacteria, as well as the presence of nitrite oxidizing bacteria closely related to the genus Nitrospira. In addition, two Legionella-like species were detected with 16S rDNA genus-specific primers: Tatlockia micdadei, and Legionella Like Amoebal Pathogen 1 (LLAP1). To date, sequences of eukaryotic microorganisms from clones obtained using universal 18S rDNA primers show similarity to sequences of Gymnodinium and Plectus species. Determination of the predominant protozoan species within the distribution water will allow the identification of possible hosts for Legionella species and other opportunistic pathogens.