Changes of Concentration and Cultivability of Escherichia Coli in Biofilm of a Drinking Water Distribution Network
Biofilms IV 2010
Linda Mežule, Simona Larsson, Tālis Juhna

Harbored in biofilm of oligotrophic environment Escherichia coli cells lose their ability to grow on conventional culture media. In this state E.coli has been found in several drinking water distribution networks, hence the rising concern about possible risk of recontamination. However, it is not possible to properly address this concern before the fate of these fecal bacteria in water supply systems is understood. Previous laboratory scale studies have shown that E.coli can grow in water in presence of native biota at concentration of assimilable organic carbon (AOC) and temperature typical for some of drinking water supplies. In this study drinking water from a water supply having a temperature of 20°C containing about 400 µg-AOC/l was fed in a biofilm reactor (Propella™). Weekly samples from water and biofilm were analyzed using the culture based methods and fluoresce in-situ hybridization combined with Direct Viable Count. Results showed that no cultivable E. coli was found in the biofilm. However, the total concentration of E.coli in biofilm gradually increased, reaching the maximum after two weeks (460 cells/cm2), after which it decreased below the detection limit (below 3 cells/cm2). The occurrence of E.coli has been previously linked with repair works. By examining the repair data and applying computer modeling of the flow it was concluded that this was not the case in this study. The possible origins of E.coli in the network could be from surrounding environment or regrowth.


Atslēgas vārdi
e.coli, drinking water, viability

Mežule, L., Larsson, S., Juhna, T. Changes of Concentration and Cultivability of Escherichia Coli in Biofilm of a Drinking Water Distribution Network. No: Biofilms IV, Lielbritānija, Winchester, 1.-3. septembris, 2010. Southampton: University of Southampton, 2010, 37.-37.lpp.

Publikācijas valoda
English (en)
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