Flow-cytometric total bacterial cell counts as a descriptive microbiological parameter for drinking water treatment processes

Frederik Hammes, Michael Berney, Yingying Wang, Marius Vital, Oliver Köster, Thomas Egli

Research output: Contribution to journalArticle

311 Citations (Scopus)

Abstract

There are significantly more microbial cells in drinking water than what can be cultured on synthetic growth media. Nonetheless, cultivation-based heterotrophic plate counts (HPCs) are used worldwide as a general microbial quality parameter in drinking water treatment and distribution. Total bacterial cell concentrations are normally not considered during drinking water treatment as a design, operative or legislative parameters. This is mainly because easy and rapid methods for quantification of total bacterial cell concentrations have, up to now, not been available. As a consequence, the existing lack of data does not allow demonstrating the practical value of this parameter. In this study, we have used fluorescence staining of microbial cells with the nucleic acid stain SYBR® Green I together with quantitative flow cytometry (FCM) to analyse total cell concentrations in water samples from a drinking water pilot plant. The plant treats surface water (Lake Zürich) through sequential ozonation, granular active carbon (GAC) filtration and membrane ultrafiltration (UF). The data were compared with adenosine tri-phosphate (ATP) measurements and conventional HPCs performed on the same water samples. We demonstrated that the impact of all three major treatment steps on the microbiology in the system could accurately be described with total cell counting: (1) ozonation caused chemical destruction of the bacterial cells; (2) GAC filtration facilitated significant regrowth of the microbial community; and (3) membrane UF physically removed the bacterial cells from the water. FCM typically detected 1-2 log units more than HPC, while ATP measurements were prone to interference from extracellular ATP released during the ozonation step in the treatment train. We have shown that total cell concentration measured with FCM is a rapid, easy, sensitive and importantly, a descriptive parameter of several widely applied drinking water treatment processes.

Original languageEnglish (US)
Pages (from-to)269-277
Number of pages9
JournalWater Research
Volume42
Issue number1-2
DOIs
StatePublished - Jan 2008
Externally publishedYes

Fingerprint

Water treatment
Potable water
flow cytometry
Ozonization
Flow cytometry
phosphate
ultrafiltration
Phosphates
Ultrafiltration
drinking water
membrane
carbon
microbiology
Membranes
nucleic acid
regrowth
Microbiology
Water
Carbon
water

Keywords

  • Adenosine tri-phosphate (ATP)
  • Drinking water
  • Flow cytometry
  • Heterotrophic plate counts (HPCs)
  • Total cell concentration

ASJC Scopus subject areas

  • Earth-Surface Processes

Cite this

Flow-cytometric total bacterial cell counts as a descriptive microbiological parameter for drinking water treatment processes. / Hammes, Frederik; Berney, Michael; Wang, Yingying; Vital, Marius; Köster, Oliver; Egli, Thomas.

In: Water Research, Vol. 42, No. 1-2, 01.2008, p. 269-277.

Research output: Contribution to journalArticle

Hammes, Frederik ; Berney, Michael ; Wang, Yingying ; Vital, Marius ; Köster, Oliver ; Egli, Thomas. / Flow-cytometric total bacterial cell counts as a descriptive microbiological parameter for drinking water treatment processes. In: Water Research. 2008 ; Vol. 42, No. 1-2. pp. 269-277.
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