Commercial point-of-use (PoU) drinking water filters are widely used to remove contaminants, including disinfection byproducts (DBPs), from household tap water.  Previously, our lab found chlorinated phenols (a DBP) promote expression of antibiotic resistance in Pseudomonas aeruginosa. As activated carbon in PoU filters accumulate chlorophenols, bacteria colonizing PoU devices may experience long-term DBP exposure.  This study evaluates the antibiotic resistance (AR) behavior of influent, filter-associated, and effluent bacteria. Simulating normal house, PoU devices were operated for two months with tap water spiked with 0, 50, and 100 ng/L pentachlorophenol (PCP).  PCP breakthrough was never observed in the effluent.  Phenotypic evaluation showed effluent bacteria exhibited no AR behaviors, only enhanced sensitivity to tetracycline in the filter receiving 100 ng/L PCP.  Using DNA pyrosequencing, the microbial communities of the influent, effluent, and filter fabric that surrounds the influent side of the activated carbon block show distinct community structures (see Figure). Mycobacterium, the most abundant operational taxonomic unit (OTU) (OTU has 97% similarity in DNA evaluated) on the fabric, is potentially pathogenic and known to be chlorine-resistant. We conclude that effluent communities did not demonstrate phenotypic AR behavior, possibly from limited PCP exposure. Using genomic methods, we are further evaluating genotypic differences in AR gene composition of influent, filter-associated and effluent bacteria under varied PCP exposure.Figure: Relative abundance of microbial communities.  Each color represents an OTU, identified to family.

Effect of disinfection by-products on antibiotic resistance in the bacterial communities of point-of-use (PoU) drinking water filters

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.