Browsing by Author "LaPara, Timothy M."

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Detection and enumeration of haloacetic acid-degrading bacteria in drinking water distribution systems using dehalogenase genes
(2009-09) Leach, Lynne H.; Zhang, Ping; LaPara, Timothy M.; Hozalski, Raymond M.; Camper, Anne K.
Aims: To develop a PCR-based tracking method for the detection of a subset of bacteria in drinking water distribution systems capable of degrading haloacetic acids (HAAs). Methods and Results: Published degenerate PCR primers were used to determine that 54% of tap water samples (7/13) were positive for a deh gene, indicating that drinking water distribution systems may harbour bacteria capable of HAA degradation. As the published primer sets were not sufficiently specific for quantitative PCR, new primers were designed to amplify dehII genes from selected indicator strains. The developed primer sets were effective in directly amplifying dehII genes from enriched consortia samples, and the DNA extracted from tap water provided that an additional nested PCR step for detection of the dehII gene was used. Conclusions: This study demonstrates that drinking water distribution systems harbour microbes capable of degrading HAAs. In addition, a quantitative PCR method was developed to detect and quantify dehII genes in drinking water systems. Significance and Impact of the Study: The development of a technique to rapidly screen for the presence of dehalogenase genes in drinking water distribution systems could help water utilities determine if HAA biodegradation is occurring in the distribution system.
Isolation and characterization of haloacetic acid-degrading Afipia spp. from drinking water
(2009-08) Zhang, Ping; Hozalski, Raymond M.; Leach, Lynne H.; Camper, Anne K.; Goslan, Emma H.; Parsons, Simon A.; Xie, Yuefeng F.; LaPara, Timothy M.
Haloacetic acids are a class of disinfection byproducts formed during the chlorination and chloramination of drinking water that have been linked to several human health risks. In this study, we isolated numerous strains of haloacetic aciddegrading Afipia spp. from tap water, the wall of a water distribution pipe, and a granular activated carbon filter treating prechlorinated water. These Afipia spp. harbored two phylogenetically distinct groups of a-halocarboxylic acid dehalogenase genes that clustered with genes previously detected only by cultivationindependent methods or were novel and did not conclusively cluster with the previously defined phylogenetic subdivisions of these genes. Four of these Afipia spp. simultaneously harbored both the known classes of a-halocarboxylic acid dehalogenase genes (dehI and dehII), which is potentially of importance because these bacteria were also capable of biodegrading the greatest number of different haloacetic acids. Our results suggest that Afipia spp. have a beneficial role in suppressing the concentrations of haloacetic acids in tap water, which contrasts the historical (albeit erroneous) association of Afipia sp. (specifically Afipia felis) as the causative agent of cat scratch disease.