title: Automated dead-end ultrafiltration of large volume water samples to enable detection of low-level targets and reduce sample variability.
abstract: OBJECTIVE
  A Portable Multi-use Automated Concentration System (PMACS) concentrates micro-organisms from large volumes of water through automated dead-end ultrafiltration and backflushing. The ability to detect microbial targets from ground, surface and cooling tower waters collected using standard methods was compared with samples from the PMACS in this study.
  
  
  RESULTS
  PMACS (100 l) and standard grab samples (100-500 ml) were collected from sites in Florida and South Carolina, USA. Samples were analysed for the presence of faecal indicator bacteria (FIB; ground and surface water) or Legionella pneumophila (Lp; cooling tower water). FIB were enumerated by growth on selective media following membrane filtration or in IDEXX defined substrate media. Lp cells were detected by direct fluorescence immunoassay using FITC-labelled monoclonal antibodies targeting serogroups 1, 2, 4 and 6. FIB were found in PMACS samples from ground and surface waters when their concentrations were below detection limits in grab samples. The concentrations of Lp in cooling tower samples collected over 5 months were more consistent in PMACS samples than grab samples.
  
  
  CONCLUSIONS
  These data demonstrate that PMACS concentration is advantageous for water monitoring. FIB were detected in PMACS samples when their concentrations were below the detection limits of the standard methods used. PMACS processing provided more representative samples of cooling tower waters reducing sample variability during long-term monitoring.
  
  
  CONCLUSIONS
  This study highlights the utility of PMACS processing for enhanced monitoring of water for low-level microbial targets and for reducing sample variability in long-term monitoring programmes.
authors.affiliation: Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620-7115, USA. leskinen@usf.edu
authors.forename: S D
authors.initials: SD
authors.lastname: Leskinen
authors.forename: E A
authors.initials: EA
authors.lastname: Kearns
authors.forename: W L
authors.initials: WL
authors.lastname: Jones
authors.forename: R S
authors.initials: RS
authors.lastname: Miller
authors.forename: C R
authors.initials: CR
authors.lastname: Bevitas
authors.forename: M T
authors.initials: MT
authors.lastname: Kingsley
authors.forename: R L
authors.initials: RL
authors.lastname: Brigmon
authors.forename: D V
authors.initials: DV
authors.lastname: Lim
mesh_terms: D016983:Enterococcus / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005431:Florida; D005455:Fluorescent Antibody Technique; D060587:Groundwater / Q000382:microbiology; D016952:Legionella pneumophila / Q000302:isolation & purification; D057230:Limit of Detection; D045483:Rivers / Q000382:microbiology; D013022:South Carolina; D014462:Ultrafiltration / Q000379:methods*; D014871:Water Microbiology; D014881:Water Supply