Spatial and temporal investigation of taste and odor-producing microorganisms in Lake Saugahatchee

Abstract

Geosmin is one of the most prevalent taste and odor compounds found in drinking water and is produced by a variety of algae. Quantitative PCR (qPCR) can be used to identify and monitor the growth of geosmin producers by targeting the gene encoding for geosmin synthase. However, the accuracy of qPCR is dependent on the assays used. In this study, two newly developed assays and three from the literature were tested using environmental samples collected from 4 water bodies located in and around Auburn, Alabama. Sequencing revealed that the CGeo-1F/CGeo-1R primer set was specific to the cyanobacterial geosmin synthase gene and had a linear calibration curve from 6.15 x102 to 6.15 x 105 gene copies/mL. The other primers used in this study struggled with specificity as well as quantification ability. The 288AF/288AR, SGF1/JDR1, AMgeo-F/AMgeo-R, and ActGeo-2F/ActGeo-2R primer sets amplified the geosmin synthase gene across genera in different phyla. Furthermore, the 288AF/288AR primer set required two rounds of PCR before enough amplicon was generated for sequencing. The CGeo-1F/CGeo-1R primer set showed a good positive correlation between gene copies and geosmin in the water column (r2 = 0.47). Also, the ActGeo-2F/ActGeo-2R primer set showed a good correlation between gene copy number and geosmin concentrations measured by gas chromatography-mass spectrometry (r2 = 0.79). The use of these primers may be used by water management facilities to characterize geosmin episodes and choose management options accordingly.