Copper-Dosing Simulated Glass Water Heater Microcosms

Triplicate microcosms were inoculated with PEX-b pipe coupons containing mature biofilms containing Legionella pneumophila (Lp) and examined over an 11-month period of exposure to different levels of copper (0, 4, 30, 250, and 2000 ppb). Microcosms underwent a 6 month acclimating phase where Lp was cross-inoculated between the microcosm 10 times. The aim of the study was to assess Legionella growth using Legiolert and ddPCR. Triplicate microcosms acted vastly different from one another as far as Lp growth but similar in terms of TCC and M. Avium. 16S rRNA amplicon sequencing was conducted at the end of the experiment across 3 sampling days (3 and then 4 days apart) to explore differences between triplicates.