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PHYLOGENETIC ANALYSIS OF 16S RRNA GENE SEQUENCES REVEALS THE PREVALENCE OF MYCOBACTERIA SP., ALPHA-PROTEOBACTERIA, AND UNCULTURED BACTERIA IN DRINKING WATER MICROBIAL COMMUNITIES
Citation:
REVETTA, R. P., B. W. HUMRIGHOUSE, J. W. SANTO-DOMINGO, A. C. PEMBERTON, AND D. B. OERTHER. PHYLOGENETIC ANALYSIS OF 16S RRNA GENE SEQUENCES REVEALS THE PREVALENCE OF MYCOBACTERIA SP., ALPHA-PROTEOBACTERIA, AND UNCULTURED BACTERIA IN DRINKING WATER MICROBIAL COMMUNITIES. Presented at American Society for Microbiology - General Meeting, Toronto, ON, CANADA, May 21 - 25, 2007.
Description:
Previous studies have shown that culture-based methods tend to underestimate the densities and diversity of bacterial populations inhabiting water distribution systems (WDS). In this study, the phylogenetic diversity of drinking water bacteria was assessed using sequence analysis of 16S rDNA clone libraries. Total community DNA was extracted from water samples collected at different times and locations in a metropolitan distribution system. Phylogenetic analyses of 990 clones revealed that actinobacteria and proteobacteria were the most predominant bacterial groups in the samples analyzed. Within the actinobacterial group, approximately 60% of the sequences were identified as mycobacterial species, with clones closely related to M. gordonae, M. sacrum, and M. mucogenicum showing sequence similarities of 98 to 100%. While members of the Mycobacterium genus are known to be pathogenic and have been isolated from drinking water samples, the public health relevance of these mycobacterial species in drinking water has yet to be determined. Proteobacterial sequences were obtained in all of the clone libraries with approximately 19% of all sequences being closely related to alpha-proteobacteria, whereas, beta- and gamma-proteobacteria were only 2% and 3%, respectively. A significant portion of the sequences (i.e., 18%) showed less than 97% identity with sequences present in public databases. Most of the latter sequences are closely related to drinking water sequences retrieved from previous studies, suggesting that these bacteria are normal WDS inhabitants. The results of this study, along with those from earlier studies, are helping us to better understand the molecular diversity and population dynamics of WDS microbial communities.