Application of quantitative real-time PCR with dual-labeled hydrolysis probes to microbial water quality monitoring.

Issues of water quality are a global problem with potentially devastating results in communities if microbial levels are not monitored and controlled effectively.This is especially true with the potential threat of bioterrorist contamination of water supplies.This study presents a method for quantifying microbial water pathogens by 5' nuclease real-time polymerase chain reaction analysis, thus decreasing the assay time (under 2 h for completion of thermal cycling and analysis) and increasing the sensitivity and precision of detection as compared with traditionally used assays. We have quantified Escherichia coli, toxigenic E. coli O157:H7, the microcystin-producing cyanobacterium Microcystis aeruginosa, and the protozoan parasite Giardia lamblia. Our measurements have detected as few as three cells per sample for the bacterial targets and one cell per sample for G. lamblia. The quantification of total E. coli and microcystin-producing cyanobacteria has been extended to the analysis of environmental samples.