title: Sulfate Reducing Bacteria and Mycobacteria Dominate the Biofilm Communities in a Chloraminated Drinking Water Distribution System.
abstract: The quantity and composition of bacterial biofilms growing on 10 water mains from a full-scale chloraminated water distribution system were analyzed using real-time PCR targeting the 16S rRNA gene and next-generation, high-throughput Illumina sequencing. Water mains with corrosion tubercles supported the greatest amount of bacterial biomass (n = 25; geometric mean = 2.5 × 10(7) copies cm(-2)), which was significantly higher (P = 0.04) than cement-lined cast-iron mains (n = 6; geometric mean = 2.0 × 10(6) copies cm(-2)). Despite spatial variation of community composition and bacterial abundance in water main biofilms, the communities on the interior main surfaces were surprisingly similar, containing a core group of operational taxonomic units (OTUs) assigned to only 17 different genera. Bacteria from the genus Mycobacterium dominated all communities at the main wall-bulk water interface (25-78% of the community), regardless of main age, estimated water age, main material, and the presence of corrosion products. Further sequencing of the mycobacterial heat shock protein gene (hsp65) provided species-level taxonomic resolution of mycobacteria. The two dominant Mycobacteria present, M. frederiksbergense (arithmetic mean = 85.7% of hsp65 sequences) and M. aurum (arithmetic mean = 6.5% of hsp65 sequences), are generally considered to be nonpathogenic. Two opportunistic pathogens, however, were detected at low numbers: M. hemophilum (arithmetic mean = 1.5% of hsp65 sequences) and M. abscessus (arithmetic mean = 0.006% of hsp65 sequences). Sulfate-reducing bacteria from the genus Desulfovibrio, which have been implicated in microbially influenced corrosion, dominated all communities located underneath corrosion tubercules (arithmetic mean = 67.5% of the community). This research provides novel insights into the quantity and composition of biofilms in full-scale drinking water distribution systems, which is critical for assessing the risks to public health and to the water supply infrastructure.
authors.affiliation: †Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States.|‡Water Resources Sciences Graduate Program, University of Minnesota, St. Paul, Minnesota 55108, United States.
authors.forename: C Kimloi
authors.initials: CK
authors.lastname: Gomez-Smith
authors.affiliation: †Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States.|§BioTechnology Institute, University of Minnesota, St. Paul, Minnesota 55108, United States.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: LaPara
authors.affiliation: †Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States.|§BioTechnology Institute, University of Minnesota, St. Paul, Minnesota 55108, United States.
authors.forename: Raymond M
authors.initials: RM
authors.lastname: Hozalski
mesh_terms: D018441:Biofilms; D002700:Chloramines / Q000737:chemistry; D003343:Corrosion; D003901:Desulfovibrio / Q000235:genetics / Q000302:isolation & purification; D060766:Drinking Water / Q000737:chemistry / Q000382:microbiology*; D059013:Microbial Consortia / Q000235:genetics; D008910:Minnesota; D009161:Mycobacterium / Q000235:genetics / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013431:Sulfates / Q000378:metabolism*; D014871:Water Microbiology; D018508:Water Purification; D014881:Water Supply
chemical_list: D002700:Chloramines; D060766:Drinking Water; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; C030816:chloramine