title: Assessing the impact of water treatment on bacterial biofilms in drinking water distribution systems using high-throughput DNA sequencing.
abstract: Biofilm control in drinking water distribution systems (DWDSs) is crucial, as biofilms are known to reduce flow efficiency, impair taste and quality of drinking water and have been implicated in the transmission of harmful pathogens. Microorganisms within biofilm communities are more resistant to disinfection compared to planktonic microorganisms, making them difficult to manage in DWDSs. This study evaluates the impact of four unique drinking water treatments on biofilm community structure using metagenomic DNA sequencing. Four experimental DWDSs were subjected to the following treatments: (1) conventional coagulation, (2) magnetic ion exchange contact (MIEX) plus conventional coagulation, (3) MIEX plus conventional coagulation plus granular activated carbon, and (4) membrane filtration (MF). Bacterial biofilms located inside the pipes of each system were sampled under sterile conditions both (a) immediately after treatment application ('inlet') and (b) at a 1 km distance from the treatment application ('outlet'). Bacterial 16S rRNA gene sequencing revealed that the outlet biofilms were more diverse than those sampled at the inlet for all treatments. The lowest number of unique operational taxonomic units (OTUs) and lowest diversity was observed in the MF inlet. However, the MF system revealed the greatest increase in diversity and OTU count from inlet to outlet. Further, the biofilm communities at the outlet of each system were more similar to one another than to their respective inlet, suggesting that biofilm communities converge towards a common established equilibrium as distance from treatment application increases. Based on the results, MF treatment is most effective at inhibiting biofilm growth, but a highly efficient post-treatment disinfection regime is also critical in order to prevent the high rates of post-treatment regrowth.
authors.affiliation: Australian Centre for Ancient DNA (ACAD), University of Adelaide, Darling Building, North Terrace, Adelaide, SA 5000, Australia. Electronic address: Jennifer.shaw@adelaide.edu.au.
authors.forename: Jennifer L A
authors.initials: JL
authors.lastname: Shaw
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Monis
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia.
authors.forename: Rolando
authors.initials: R
authors.lastname: Fabris
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia.
authors.forename: Lionel
authors.initials: L
authors.lastname: Ho
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia.
authors.forename: Kalan
authors.initials: K
authors.lastname: Braun
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia.
authors.forename: Mary
authors.initials: M
authors.lastname: Drikas
authors.affiliation: Australian Centre for Ancient DNA (ACAD), University of Adelaide, Darling Building, North Terrace, Adelaide, SA 5000, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Cooper
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D018441:Biofilms; D060766:Drinking Water / Q000382:microbiology*; D016680:Genome, Bacterial; D059014:High-Throughput Nucleotide Sequencing; D054892:Metagenome; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013021:South Australia; D018508:Water Purification / Q000592:standards*
chemical_list: D060766:Drinking Water; D012336:RNA, Ribosomal, 16S
keywords: Bacteria; Biofilm; DNA sequencing; Drinking water treatment; Metagenomics