Detection and enumeration of haloacetic acid-degrading bacteria in drinking water distribution systems using dehalogenase genes

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.