Aims: Escherichia coli is the faecal indicator species recommended by the US Environmental Protection Agency (USEPA) for monitoring fresh recreational water. Viable but nonculturable (VBNC) E. coli are living cells that are dormant and not culturable using standard microbiological cultivation methods. This study reports a comparison between the mTEC culture method recommended by USEPA for E. coli enumeration and a fluorescent antibody‐direct viable count (FA‐DVC) method to visualize living E. coli cells with a microscope.
Methods and Results: Escherichia coli, faecal coliforms and Enterococcus were detected using standard methods recommended by the USEPA. VBNC E. coli was visualized with FA‐DVC. Results were analysed with standard statistical methods (Pearson correlation; paired‐sample t‐test). Significantly higher numbers of E. coli were detected using the FA‐DVC method than using the mTEC method. Escherichia coli results were also compared with faecal coliform (mFC broth) and Enterococcus (mEI agar) counts in the same samples.
Conclusions: The results of this comparative study demonstrate that E. coli can be present in higher numbers than what are detected with standard culture methods.
Significance and Impact of the Study: This study re‐emphasizes the need for a rapid, accurate and precise method for detecting health risks to humans who use recreational waters.
S U M M A R YParamecia belonging to certain strains of Parameciunz aurelia (syngens I , 2 and 8) were transferred from dual culture with bacteria to axenic media, where the growth of some stocks continued, with weekly subculturing. The only axenically grown stock found to be capable of supporting growth of mu particles indefinitely was stock 138 (syngen 8).Lambda and mu particles from axenically grown Paramecium aurelia were cultivated in vitro in a highly complex medium at 27O under aerobic conditions. The particles retained their characteristic killing action on certain P. aurelia stocks but could not infect sensitive paramecia. The particles divided at approximately one fission per day and achieved a maximum density of only 16-20 x 103/ml. The implications of these studies for the interaction of the nuclear genes and the killer particles are discussed.
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