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POPULATION DIVERSITY IN MODEL DRINKING WATER BIOFILMS RECEIVING CHLORINE OR MONOCHLORAMINE RESIDUAL
WILLIAMS, M., J. SANTO-DOMINGO, AND M. C. MECKES. POPULATION DIVERSITY IN MODEL DRINKING WATER BIOFILMS RECEIVING CHLORINE OR MONOCHLORAMINE RESIDUAL. Presented at American Society for Microbiology Annual Meeting, Atlanta, GA, June 03 - 09, 2005.
To inform the public
Most water utilities add monochloramine or chlorine as a residual disinfectant in potable water distribution systems (WDS) to control bacterial regrowth. While monochloramine is considered more stable than chlorine, little is known about the fate of this disinfectant or the effect it has on microbial populations when it is in contact with WDS biofilms. Community structure of WDS biofilms exposed to disinfectants was assessed after developing model biofilms from unamended distribution water for 10 weeks on polycarbonate slides within annular reactors while receiving either chlorine, monochloramine, or no residual disinfectant. Eubacterial composition was examined through sequence analysis of the 16S rRNA gene. The model WDS biofilm exposed to monochloramine residual contained mainly Mycobacterium and Dechloromonas sequences, while the other three biofilms contained a variety of sequences related to alpha- and beta-proteobacteria, as well as other phylogenetic groups. Additionally, after biofilm was established, monochloramine residual consistently disappeared from the reactor, even with increasing concentrations of monochloramine in the water entering the system, while chlorine residual remained steady throughout the experiment. Under these conditions, distribution water carrying a monochloramine residual selects for the growth of Mycobacterium species in WDS biofilms.