Two molecular methods, denaturing gradient gel electrophoresis (DGGE) and quantitative real-time
polymerase chain reaction (qPCR) with the Universal ProbeLibrary (UPL) probe, were developed and
used for the characterization and quantification of several microcystin producers in Moo-Tan Reservoir
(MTR), Taiwan and its associated water treatment plant (Shih-Men Water Treatment Plant, SMWTP).
Internal transcribed spacer (ITS) sequence, a highly diversified region between the 16S rRNA and 23S
rRNA genes, was used to further identify the isolated strains from MTR and also used in DGGE for the
detection of the specific DNA fragments and biomarkers for 11 strains observed in MTR. These ITSDGGE
biomarkers were successfully applied to monitor the community changes of potential toxigenic
Microcystis sp. over a period of five years. Two highly specific primers were combined with UPL probes
to measure microcystins synthesis gene (mcyB) and phycocyanin intergenic spacer region (cpcB)
concentrations in water samples. The copy concentrations of UPL-mcyB and UPL-cpcB correlated well
with MC-RR concentrations/water temperature and Microcystis sp. cell numbers in the water samples,
respectively. For SMWTP, toxin concentrations were low, but the DGGE bands clearly demonstrated
the presence of potential microcystin producers in both water treatment plants and finished water
samples. It was demonstrated that toxigenic Microcystis sp. may penetrate through the treatment
processes and pose a potential risk to human health in the drinking water systems.
