Establishment of quantitative PCR methods for the quantification of geosmin-producing potential and Anabaena sp. in freshwater systems
Abstract
Geosmin has often been associated with off-flavor problems in drinking water, with Anabaena sp. as the major producer. Rapid on-site detection of geosmin producers as well as geosmin is important for timely management responses to potential off-flavor events. In this study, quantitative polymerase chain reaction (qPCR) methods were developed to detect Anabaena sp. and geosmin production potential by designing two primer sets targeting the rpoC1 gene (ARG) and geosmin synthase gene (GSG) in freshwater systems. ARG density determined by qPCR was highly related to microscopic cell counts (\(r^2 = 0.726\), \(p < 0.001\)), with limits of detection and quantification of 0.02 and 0.2 pg DNA, respectively. The relationship between geosmin concentrations measured by gas chromatography-mass spectrometry and GSG copy number was also established (\(r^2 = 0.742\), \(p < 0.001\)), with similar detection limits. The two protocols measured different levels of ARG and GSG copies across freshwater systems with diverse ecological conditions, showing their potential for environmental monitoring. Compared with microscopy and GC-MS, qPCR reduced time to results from several days to a few hours and required less taxonomic expertise.