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Comparison of Microbial Communities in a Simulated Chloraminated Drinking Water Distribution System Subjected to Episodes of Nitrification (poster)
Citation:
Revetta, R., C. Bennett-Stamper, K. Kleier, S. Pfaller, D. King, J. Pressman, D. Wahman, AND V. Gomez-Alvarez. Comparison of Microbial Communities in a Simulated Chloraminated Drinking Water Distribution System Subjected to Episodes of Nitrification (poster). #1260. American Society for Microbiology, New Orleans, LA, May 30 - June 02, 2015.
Impact/Purpose:
The current research examined the Bacterial populations in a simulated chloraminated drinking water distribution system. The research used next generation high-throughput technology and culture-dependent assays to:(1)determine the extent to which the community structure varies temporally and spatially within the distribution system, and (2)describe the response of microbial communities to a disturbance caused by changes in the operational parameters of the distribution system.
Description:
Bacterial populations were examined in a simulated chloraminated drinking water distribution system (i.e. PVC pipe loop). After six months of continuous operation, coupons were incubated in CDC reactors receiving water from the simulated system to study biofilm development. The study was organized into five distinct operational schemes: (1) PRE-MODIFIED; system stabilization, (2)STANDARD I; stable chloramine residual, (3) FAILURE; complete nitrification and minimal chloramine residual, (4) RESTORE; chlorine burn, and (5) STANDARD II; stable chloramine residual. Bulk water and biofilm samples were collected and analyzed for water quality parametersand community composition. No change in biomass (protein and ATP assays) in bulk water and biofilm samples was detected during the STANDARD I scheme, while an increase in biofilms was detected after 80 days (FAILURE, i.e. nitrification) followed by a decrease after a chlorine burn with a final increase to previous values (STANDARD I) during the STANDARD II scheme. The estimated populations of heterotrophs (HPC) were constant for all samples. Approximately 68% of the total diversity in the viable (PMA treated) microbial community was associated with the class Alphaproteobacteria, Actinobacteria, and Gammaproteobacteria. Community comparison showed significant differences in functional and taxonomic structures based on source (e.g. disinfectant treatment) and operational schemes. For example, members of the family Methylobacteriaceae (22%) dominated chlorine-treated water (i.e. municipal water), while early stages of operation (PRE-MODIFIED) were dominated by Novosphingobium (38%). Environmental Mycobacterium-like OTUs peaked during the STANDARD I scheme (40%) but decreased to <10% in later periods, andan increase in the abundance of nitrifying bacteria Nitrospira (<0.3% to 4%) was observed during the FAILURE scheme. Ammonia-oxidizing bacteria related to nitrosomonas were detected during nitrification. In addition, genes associated with multiple disinfectant resistance mechanisms and virulence factors, such as antibiotic resistance mechanisms, were found to be a component of the core genome of bacterial isolates.
