title: Effect of chlorine and temperature on free-living protozoa in operational man-made water systems (cooling towers and hot sanitary water systems) in Catalonia.
abstract: In recent decades, free-living protozoa (FLP) have gained prominence as the focus of research studies due to their pathogenicity to humans and their close relationship with the survival and growth of pathogenic amoeba-resisting bacteria. In the present work, we studied the presence of FLP in operational man-made water systems, i.e. cooling towers (CT) and hot sanitary water systems (HSWS), related to a high risk of Legionella spp. outbreaks, as well as the effect of the biocides used, i.e. chlorine in CT and high temperature in HSWS, on FLP. In CT samples, high-chlorine concentrations (7.5 ± 1.5 mg chlorine L(-1)) reduced the presence of FLP by 63.8 % compared to samples with low-chlorine concentrations (0.04 ± 0.08 mg chlorine L(-1)). Flagellates and amoebae were observed in samples collected with a level of 8 mg chlorine L(-1), which would indicate that some FLP, including the free-living amoeba (FLA) Acanthamoeba spp., are resistant to the discontinuous chlorine disinfection method used in the CT studied. Regarding HSWS samples, the amount of FLP detected in high-temperatures samples (53.1 ± 5.7 °C) was 38 % lower than in low-temperature samples (27.8 ± 5.8 °C). The effect of high temperature on FLP was chiefly observed in the results obtained by the culture method, in which there was a clear reduction in the presence of FLP at temperatures higher than 50 °C, but not in those obtained by PCR. The findings presented here show that the presence of FLP in operational man-made water systems should be taken into account in future regulations.
authors.affiliation: Laboratory of Protistology, Departament de Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Canals
authors.forename: Alejandra
authors.initials: A
authors.lastname: Serrano-Suárez
authors.forename: Humbert
authors.initials: H
authors.lastname: Salvadó
authors.forename: Javier
authors.initials: J
authors.lastname: Méndez
authors.forename: Sílvia
authors.initials: S
authors.lastname: Cervero-Aragó
authors.forename: Vicenç
authors.initials: V
authors.lastname: Ruiz de Porras
authors.forename: Jordi
authors.initials: J
authors.lastname: Dellundé
authors.forename: Rosa
authors.initials: R
authors.lastname: Araujo
mesh_terms: D000048:Acanthamoeba / Q000302:isolation & purification*; D056893:Alveolata / Q000302:isolation & purification*; D000656:Amoeba; D001419:Bacteria; D002713:Chlorine; D004202:Disinfectants; D004203:Disinfection / Q000379:methods*; D006358:Hot Temperature; D007875:Legionella; D013030:Spain; D013696:Temperature; D014867:Water / Q000469:parasitology
chemical_list: D004202:Disinfectants; D014867:Water; D002713:Chlorine