TY - JOUR
T1 - Flow-cytometric total bacterial cell counts as a descriptive microbiological parameter for drinking water treatment processes
AU - Hammes, Frederik
AU - Berney, Michael
AU - Wang, Yingying
AU - Vital, Marius
AU - Köster, Oliver
AU - Egli, Thomas
N1 - Funding Information:
The authors acknowledge financial assistance from the Eawag Wave21 project and the 6th EU framework project TECHNEAU (018320), as well as technical and scientific contributions of I. Hülshoff, J. Traber and S. Meylan.
PY - 2008/1
Y1 - 2008/1
N2 - 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.
AB - 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.
KW - Adenosine tri-phosphate (ATP)
KW - Drinking water
KW - Flow cytometry
KW - Heterotrophic plate counts (HPCs)
KW - Total cell concentration
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U2 - 10.1016/j.watres.2007.07.009
DO - 10.1016/j.watres.2007.07.009
M3 - Article
C2 - 17659762
AN - SCOPUS:37449010517
SN - 0043-1354
VL - 42
SP - 269
EP - 277
JO - Water Research
JF - Water Research
IS - 1-2
ER -