Cross-flow microfiltration system for rapid enrichment of bacteria in water

Permanent monitoring of waterborne pathogens is important for securing the hygiene of water. Enumerating bacteria in water at low concentrations and minute quantities demands rapid and efficient enrichment methods in order to improve the signal-to-noise ratio of subsequent determination methods. In this work an automated cross-flow microfiltration (CFM) system is presented which is usable in the field to concentrate large volumes of environmental water for analytical purposes. It was designed as a rapid enrichment apparatus achieving high recovery and high concentration factors. The efficiency of the CFM system was studied for E. coli spiked in a 10-L tap water sample. By this technique, a 10-L water sample was concentrated by a factor of 200 in 15 min. The high and consistent recovery of 91.3 +/- 5.4% living cells in the concentration range 0.01 and 100 cfu mL(-1) is suitable for rapid enumeration of bacteria in water.