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Bacterial Composition of Biofilms Collected From Two Service Areas in a Metropolitan Drinking Water Distribution System
Revetta, R., V. Gomez-Alvarez, T. Gerke, J. Santodomingo, AND N. Ashbolt. Bacterial Composition of Biofilms Collected From Two Service Areas in a Metropolitan Drinking Water Distribution System. Presented at American Society for Microbiology, Poster #2230, Boston, MA, May 17 - 20, 2014.
These results provide an ecological insight into biofilm bacterial diversity in chlorine-treated drinking water biofilms.
The development and succession of bacteria were examined by 16S rRNA gene clone libraries generated from various biofilms within a metropolitan water distribution system. Biofilms were obtained from off-line devices using polycarbonate coupons from annular reactors incubated for up to eighteen months in chlorine-treated drinking water. The distribution system service area is fed by two different source waters (i.e., groundwater, GW and surface water, SW) and two different treatment facilities. Since different source waters have unique water quality properties (e.g., pH, temperature, chlorine residual), and different treatment processes (e.g., filtration) have been shown to play an important role in shaping the bacterial community in the distribution system, we hypothesize that biofilm microbial communities at each service area will harbor distinct and diverse bacterial communities. Samples were obtained from (1) discharge of the GW treatment facility (B_WTP); (2) pump station approximately 4 hours water age from SW treatment facility (MS_PS); and (3) pump station approximately 24 hours water age from SW treatment facility (WH_PS). Overall, 31 OTUs (965 sequences) were shared between MS_PS and WH_PS, while 34 OTUs (964 sequences) were shared between WH_PS and B_WTP, and 27 OTUs (785 sequences) were shared between MS_PS and B_WTP. Significant differences were observed between GW and SW communities as measured using non-metric dimensional scaling of 16S rRNA bacterial clone libraries based on Bray-Curtis dissimilarity. OTU representatives that explained 68% (SIMPER analysis) of the dissimilarity were associated with Beta proteobacteria (22.6%), Alpha Proteobacteria (18.9%), Actinobacteria (16.8%), Gamma Proteobacteria (7.2%) and Firmicutes (2.4%). Limnobacter (17% total; 30% GW; <1% SW), Mycobacterium (15% total; 12% GW; 29% SW), and Sphingopyxis (6% total; 10% GW; <1% SW) were the three most abundant dominant phylotypes from shared OTUs. Early stages of GW biofilm formation (3-6 months) were dominated by Limnobacter, while Mycobacterium was most abundant at 9 months incubation in both GW and SW biofilms. These results provide an ecological insight into biofilm bacterial diversity in chlorine-treated drinking water biofilms.