title: Development and laboratory-scale testing of a fully automated online flow cytometer for drinking water analysis.
abstract: Accurate and sensitive online detection tools would benefit both fundamental research and practical applications in aquatic microbiology. Here, we describe the development and testing of an online flow cytometer (FCM), with a specific use foreseen in the field of drinking water microbiology. The system incorporated fully automated sampling and fluorescent labeling of bacterial nucleic acids with analysis at 5-min intervals for periods in excess of 24 h. The laboratory scale testing showed sensitive detection (< 5% error) of bacteria over a broad concentration range (1 × 10(3) -1 × 10(6) cells mL(-1) ) and particularly the ability to track both gradual changes and dramatic events in water samples. The system was tested with bacterial pure cultures as well as indigenous microbial communities from natural water samples. Moreover, we demonstrated the possibility of using either a single fluorescent dye (e.g., SYBR Green I) or a combination of two dyes (SYBR Green I and Propidium Iodide), thus broadening the application possibilities of the system. The online FCM approach described herein has considerable potential for routine and continuous monitoring of drinking water, optimization of specific drinking water processes such as biofiltration or disinfection, as well as aquatic microbiology research in general.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland. frederik.hammes@eawag.ch
authors.forename: Frederik
authors.initials: F
authors.lastname: Hammes
authors.forename: Tobias
authors.initials: T
authors.lastname: Broger
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Weilenmann
authors.forename: Marius
authors.initials: M
authors.lastname: Vital
authors.forename: Jakob
authors.initials: J
authors.lastname: Helbing
authors.forename: Ulrich
authors.initials: U
authors.lastname: Bosshart
authors.forename: Pascal
authors.initials: P
authors.lastname: Huber
authors.forename: Res Peter
authors.initials: RP
authors.lastname: Odermatt
authors.forename: Bernhard
authors.initials: B
authors.lastname: Sonnleitner
mesh_terms: D057205:Automation, Laboratory / Q000379:methods*; D052160:Benzothiazoles; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis; D003959:Diamines; D060766:Drinking Water / Q000032:analysis*; D004926:Escherichia coli / Q000302:isolation & purification*; D005434:Flow Cytometry / Q000379:methods*; D005456:Fluorescent Dyes; D050296:Microbial Viability; D009930:Organic Chemicals; D011419:Propidium; D011804:Quinolines; D015203:Reproducibility of Results; D013194:Staining and Labeling / Q000379:methods; D013696:Temperature; D014871:Water Microbiology
chemical_list: D052160:Benzothiazoles; D004269:DNA, Bacterial; D003959:Diamines; D060766:Drinking Water; D005456:Fluorescent Dyes; D009930:Organic Chemicals; D011804:Quinolines; C098022:SYBR Green I; D011419:Propidium