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Microbial Community Dynamics of a Simulated Chloraminated Drinking Water Distribution System Subjected to Episodes of Nitrification
Citation:
Gomez-Alvarez, V., C. Bennett-Stamper, K. Kleier, S. Pfaller, J. Pressman, D. Wahman, AND R. Revetta. Microbial Community Dynamics of a Simulated Chloraminated Drinking Water Distribution System Subjected to Episodes of Nitrification. Presented at 114th General Meeting of the American Society for Microbiology, Poster #2762, Boston, MA, May 17 - 20, 2014.
Impact/Purpose:
To present this information and results with the scientific community.
Description:
Bacterial populations were examined in a simulated chloraminated drinking water distribution system (i.e. loop). The loop (BW-AB-I) received chlorinated municipal water (BW-C) amended with ammonia (2mg/L monochloramine). After six years of continuous operation, the operational parameters were changed to reflect a well run distribution system (BW-AB-II). Copper and PVC coupons were incubated in off-line CDC reactors to study biofilm development. The loop was then subjected to episodes of nitrification, followed by a ‘chlorine burn’ by switching disinfectant from chloramine to chlorine. Bulk water and biofilm samples were collected and analyzed for: water quality parameters, to generate 16S rRNA libraries for community composition, biomass (protein and ATP), and to estimate populations of heterotrophs (HPC) and nitrifiers (qPCR). No change in biomass in water samples was detected during the study, while an increase in biofilms was detected after 80 days. HPC counts were constant for all samples. nMDS and one-way ANOSIM tests showed clustering of samples and significant differences in community structures based on disinfection types (chlorine vs chloramine) and water quality (BW-AB-I vs BW-AB-II). The community analysis revealed major differences in core populations with Alphaproteobacteria (27%), Fusobacteria (15%), Bacilli (14%) and Cyanobacteria (10%) as the most abundant in BW-C (chlorine), and Alphaproteobacteria (64%), Cyanobacteria (7%), Gammaproteobacteria (7%) and Actinobacteria (7%) the most abundant in BW-AB-I (chloramine). A shift in community composition was observed after the operational parameters were changed (BW-AB-II) with Actinobacteria (28%), Alphaproteobacteria (19%), Fusobacteriia (11%), Bacilli (8%) and Betaproteobacteria (7%). Pipe material during early colonization had no apparent effects on the microbial compositions. However, both materials underwent similar successions over time with Gammaproteobacteria dominant in early stages of colonization, while Alphaproteobacteria and Mycobacterium-like phylotypes predominant in subsequent months. Ammonia-oxidizing bacteria related to Nitrosomonas were detected during nitrification. Overall, the clustering of samples based on community profiles correlate to the shifts in water quality parameters.
