title: Multi-species biofilms defined from drinking water microorganisms provide increased protection against chlorine disinfection.
abstract: A model biofilm, formed of multiple species from environmental drinking water, including opportunistic pathogens, was created to explore the tolerance of multi-species biofilms to chlorine levels typical of water-distribution systems. All species, when grown planktonically, were killed by concentrations of chlorine within the World Health Organization guidelines (0.2-5.0 mg l(-1)). Higher concentrations (1.6-40-fold) of chlorine were required to eradicate biofilm populations of these strains, ~70% of biofilms tested were not eradicated by 5.0 mg l(-1) chlorine. Pathogenic bacteria within the model multi-species biofilms had an even more substantial increase in chlorine tolerance; on average ~700-1100 mg l(-1) chlorine was required to eliminate pathogens from the biofilm, 50-300-fold higher than for biofilms comprising single species. Confocal laser scanning microscopy of biofilms showed distinct 3D structures and multiple cell morphologies and arrangements. Overall, this study showed a substantial increase in the chlorine tolerance of individual species with co-colonization in a multi-species biofilm that was far beyond that expected as a result of biofilm growth on its own.
authors.affiliation: Department of Biological Sciences, Biofilm Research Group, University of Calgary, Alberta, Canada.
authors.forename: Monika
authors.initials: M
authors.lastname: Schwering
authors.forename: Joanna
authors.initials: J
authors.lastname: Song
authors.forename: Marie
authors.initials: M
authors.lastname: Louie
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Turner
authors.forename: Howard
authors.initials: H
authors.lastname: Ceri
mesh_terms: D001419:Bacteria / Q000254:growth & development; D018407:Bacterial Physiological Phenomena / Q000187:drug effects*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002713:Chlorine / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection; D060766:Drinking Water / Q000382:microbiology*; D018613:Microscopy, Confocal; D018508:Water Purification
chemical_list: D004202:Disinfectants; D060766:Drinking Water; D002713:Chlorine