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EFFICIENT RECOVERY OF ENTEROCOCCI FROM MARINE AND FRESH WATER BEACHES BY A 30,000 MOLECULAR WEIGHT CUTOFF HOLLOW FIBER ULTRAFILTER
Citation:
MCDANIELS, A. E., C. C. RANKIN, L. J. WYMER, A. P. DUFOUR, AND K. OSHIMA. EFFICIENT RECOVERY OF ENTEROCOCCI FROM MARINE AND FRESH WATER BEACHES BY A 30,000 MOLECULAR WEIGHT CUTOFF HOLLOW FIBER ULTRAFILTER. Presented at American Society for Microbiology General 107th Meeing, Toronto, ON, CANADA, May 21 - 25, 2007.
Impact/Purpose:
Develop a rapid (same day), sensitive and accurate method for detecting and measuring fecal contamination of recreational water.
Description:
Ultrafiltration systems have been used to concentrate pathogens from various types of fresh water samples. However, less work has been done with marine waters for the concentration of pathogens or indicator bacteria. An ultrafiltration approach to concentrate indicator bacteria such as Enterococci may be advantageous because of the ability to smaple larger volumes and concentrate multiple target organisms simultaneously. Each ten liter sample was seeded with approximately 1 x 104 cells. A peristaltic pump was used to force water through a 30,000 molecular weight cutoff hollow fiber ultrafilter (Fresenius). During the filtration process, Enterococci remained in the retentate while the filtered water was collected in the permeate. Cells were eluted from the filter by forward flushing with 0.1% Tween 80 and 0.05M glycine in PBS at 7.2 pH, followed by reverse flushing and filter shaking. Nitrogen gas was used to remove all remaining fluid. Ten liters were reduced to approximately 500 mL at a rate of l liter per minute. Aliquots from seeded initial and final concentrates were filtered, the filtgers placed on mEI agar for growth and colony counts used to calculate filter mL at a rate of 1 liter per minute. Aliquots from seeded initial and final concentrates were filtered, the filters placed on mEI agar for grown and colony counts used to calculate recoveries. Recoveries from seeded marine waters averaged 93% (n=17) from the Pacific and 64.7 (n=13) from the Atlantic Oceans, which was a significant difference (p-value=0.0185). Seeded fresh water recoveries averaged 81% (n=12). The physical-chemcial parameters of pH, turbidity, specific conductivity and salinity were within their expected ranges. In conclusion, the ultrafiltration process produced high recoveries of Enterococci from large volumes of beach waters within a reasonable time frame, was simple to operate, used inexpensive disposable filters and can be operated in the field as well as in the laboratory.