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PHYLOGENETIC AFFILIATION OF WATER DISTRIBUTION SYSTEM BACTERIAL ISOLATES USING 16S RDNA SEQUENCE ANALYSIS
Citation:
Santo Domingo, J, M C. Meckes*, B. L. Sloss, J M. Simpson*, AND D J. Reasoner*. PHYLOGENETIC AFFILIATION OF WATER DISTRIBUTION SYSTEM BACTERIAL ISOLATES USING 16S RDNA SEQUENCE ANALYSIS. Presented at Meeting of the American Society for Microbiology, Salt Lake City, UT, 5/19-23/2002.
Description:
In a previously described study, only 15% of the bacterial strains isolated from a water distribution system (WDS) grown on R2A agar were identifiable using fatty acid methyl esthers (FAME) profiling. The lack of success was attributed to the use of fatty acid databases of bacteria primarily grown on rich media. The objective of this study ws to use 16S rDNA sequence analysis to better identify WDS bacteria. A total of 43 bacterial strains were selected based on colony morphotypes from R2A plates inoculated with chlorinated feed water, discharge water, and biofilm samples taken from a distribution system simulator. A minimum of 600 bases of the 5' end of the 16S rDNA were used to identify all isolates. Four isolates were identified as Gram positive bacteria closely related to Amycolatopsis, Nocardia, and Mycobacterium subgroups. Two isolates belonged to the gamma Proteobacteria while the vast majority of the isolates were identified as alpha and beta proteobacteria. The sequences for the alpha proteobacterial strains were similar to sequences of Erythrobacter sp., Porphyrobacter sp., Sphingomonas sp. and Phenylobacterium sp., while the beta proteobacterial strins were closely related to Dechlorimonas sp., Rhodopcyclus sp., and Rhodoferas sp., Aquaspirillum sp., Hydrogenophaga sp., and Azoarcus sp. The natural abundance of these bacterial groups is unknown, however, the relative frequency of each of the proteobacterial groups was different for each sample examined. This was in agreement with danaturing gradient gel elecrophoresis anlaysis of the V3 variable region of 167S rDNA gene, that showed notable differences between the microbial community structure of biofilm samples and feed water. The results from this study showed that 16S rDNA sequence analysis is a more reliable tool for classifying WDS bacteria than FAME analysis.