Integration of hygienically relevant bacteria in drinking water biofilms grown on domestic plumbing materials

摘要: Biofilms in domestic plumbing systems can represent a reservoir for potentially pathogenic bacteria including Pseudomonas aeruginosa, Legionella pneumophila and coliform bacteria. The selection of materials utilised as well their exposure to disinfectant stress (“ageing”) may affect the extent biofilm formation, composition populations incorporation persistence hygienically relevant drinking water biofilms. presence protozoa additionally influence multiplication Drinking biofilms were grown on coupons ethylene-propylene-diene-monomer (EPDM) rubber, silane cross-linked polyethylene (PE-Xb), electron-ray PE (PE-Xc) copper under constant flow-through cold tap at ambient temperature (19.0 °C ± 3.1 °C). tested both untreated after treatment with sodium hy¬pochlorite (5 ppm, 3 bar, 40 °C, 4 weeks) or chlorine dioxide case EPDM, PE-X b c unchlorinated ≥ 6 months copper. After 14 days, spiked Enterobacter nimipressuralis (106 cells/mL each). test environmental isolates from contamination cases systems. static incubation 24 h, flow was resumed continued four weeks. Total cell count heterotrophic plate (HPC) monitored, population diversity determined using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). P. L. E. quantified, standard culture-based methods culture-independent fluorescence situ hybridisation (FISH). day-old PE-Xb, analysed total amoebal genera Acanthamoeba Hartmannella FISH. After days counts HPC values highest EPDM followed by plastic higher synthetic (EPDM, PE-Xc) compared Amoebae present all tested, Acanthamoebae being prevalent genera. Material ageing did not significantly formation diversity. inoculation, aeruginosa persisted 28 PE-Xb PE-Xc, but unable colonise any days. detected aged show significant differences regarding into Application FISH showed that often concentrations than indicating part entered viable non-culturable (VBNC) state, which they detectable culture methods. Additional investigations pure cultures be one factors inducing VBNC state Planktonic biofilm-associated became culturable again upon release chelator diethyldithiocarbamate (DDTC). The results measured are material dependent, influenced ageing. able incorporate persist plumbing. have an pathogen persistence. detection amoebae suggests these organisms interact probably serve host bacteria, least pneumophila. underestimated conventional Hygienically still hygienic relevance retain virulence regain it resuscitation.