Comparison of the microbiomes of two drinking water distribution systems—with and without residual chloramine disinfection

Background Residual disinfection is often used to suppress biological growth in drinking water distribution systems (DWDSs), but not without undesirable side effects. In this study, water-main biofilms, drinking water, and bacteria under corrosion tubercles were analyzed from a chloraminated DWDS (U...

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Main Authors: Waak, Michael B, Hozalski, Raymond M, Halle, Cynthia, LaPara, Timothy M
Format: Article
Language:English
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Summary:Background Residual disinfection is often used to suppress biological growth in drinking water distribution systems (DWDSs), but not without undesirable side effects. In this study, water-main biofilms, drinking water, and bacteria under corrosion tubercles were analyzed from a chloraminated DWDS (USA) and a no-residual DWDS (Norway). Using quantitative real-time PCR, we quantified bacterial 16S rRNA genes and ammonia monooxygenase genes (amoA) of Nitrosomonas oligotropha and ammonia-oxidizing archaea—organisms that may contribute to chloramine loss. PCR-amplified 16S rRNA genes were sequenced to assess community taxa and diversity. Results The chloraminated DWDS had lower biofilm biomass (P=1×10−6) but higher N. oligotropha-like amoA genes (P=2×10−7) than the no-residual DWDS (medians =4.7×104 and 1.1×103amoA copies cm−2, chloraminated and no residual, respectively); archaeal amoA genes were only detected in the no-residual DWDS (median =2.8×104 copies cm−2). Unlike the no-residual DWDS, biofilms in the chloraminated DWDS had lower within-sample diversity than the corresponding drinking water (P