title: Monochloramine disinfection kinetics of Nitrosomonas europaea by propidium monoazide quantitative PCR and Live/dead BacLight methods.
abstract: Monochloramine disinfection kinetics were determined for the pure-culture ammonia-oxidizing bacterium Nitrosomonas europaea (ATCC 19718) by two culture-independent methods, namely, Live/Dead BacLight (LD) and propidium monoazide quantitative PCR (PMA-qPCR). Both methods were first verified with mixtures of heat-killed (nonviable) and non-heat-killed (viable) cells before a series of batch disinfection experiments with stationary-phase cultures (batch grown for 7 days) at pH 8.0, 25 degrees C, and 5, 10, and 20 mg Cl(2)/liter monochloramine. Two data sets were generated based on the viability method used, either (i) LD or (ii) PMA-qPCR. These two data sets were used to estimate kinetic parameters for the delayed Chick-Watson disinfection model through a Bayesian analysis implemented in WinBUGS. This analysis provided parameter estimates of 490 mg Cl(2)-min/liter for the lag coefficient (b) and 1.6 x 10(-3) to 4.0 x 10(-3) liter/mg Cl(2)-min for the Chick-Watson disinfection rate constant (k). While estimates of b were similar for both data sets, the LD data set resulted in a greater k estimate than that obtained with the PMA-qPCR data set, implying that the PMA-qPCR viability measure was more conservative than LD. For N. europaea, the lag phase was not previously reported for culture-independent methods and may have implications for nitrification in drinking water distribution systems. This is the first published application of a PMA-qPCR method for disinfection kinetic model parameter estimation as well as its application to N. europaea or monochloramine. Ultimately, this PMA-qPCR method will allow evaluation of monochloramine disinfection kinetics for mixed-culture bacteria in drinking water distribution systems.
authors: United States Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio 45268, USA.
authors: David G
authors: DG
authors: Wahman
authors: Karen A
authors: KA
authors: Wulfeck-Kleier
authors: Jonathan G
authors: JG
authors: Pressman
mesh_terms: D001386:Azides / Q000378:metabolism*; D002700:Chloramines / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D050296:Microbial Viability / Q000187:drug effects*; D043370:Nitrosomonas europaea / Q000187:drug effects*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011419:Propidium / Q000031:analogs & derivatives* / Q000378:metabolism; D013997:Time Factors
chemical_list: D001386:Azides; D002700:Chloramines; D004202:Disinfectants; C533957:propidium monoazide; D011419:Propidium; C030816:chloramine