Occurrence of F-specific RNA coliphages and microbial indicators in municipal lake water

Recent studies have shown the increasing interest of F-specific RNA bacteriophages (FRNAPH) genotyping to identify major sources of faecal contamination in waters. The aim of the study was to evaluate the presence and relevance of FRNAPH genotyping in lake water. A comparison between the levels of all FRNAPH and each genogroup and that of the standard indicators of faecal pollution (total coliforms – TC and faecal (thermotolerant) coliforms – FC) was performed. Two faecal indicators were detected in lake water: total coliforms (TC) and faecal coliforms (FC). The standardized method was used to quantify these indicators and bacterial concentrations were expressed in the most probable number per 100 ml of water (MPN/10 ml). FRNAPH were determined by the single agar layer (SAL) method using the host strain Escherichia coli Famp (ATCC 700891) in accordance with U.S. EPA Methods 1602. To distinguished between RNA and DNA phages, each FRNAPH isolate was subjected to RNAse sensitivity. All FRNAPH isolates were subjected to the four SYBR Green-based real time PCRs to determine genogroups.