Application of library-independent microbial source tracking methods for identifying the sources of faecal contamination in coastal areas

摘要

Faecal contamination sources were identified in coastal areas around the Guerande-Atlantiquenpeninsula using two microbial source tracking (MST) methods: (i) Bacteroidales host-specific 16SnrRNA gene markers measured by real-time PCR and (ii) F-specific bacteriophage (FRNAPH)ngenotyping. Both methods were used on 63 water samples from 7 water courses. HF183 markernand bacteriophage genogroup II (FRNAPH II) were detected in all water samples and in thenmajority of water samples, respectively, from La Torre stream (W5), Piriac (W2), R2000 (W3) andnMazy (W7) rain water drains, and also detected, less frequently, in Le Nau drain (W4), suggestingncontamination by human faecal sources at these sites. These human markers were weaklyndetected in Pouliguen channel (W6). Furthermore, BacR and bacteriophage genogroup In(FRNAPH I) were also detected, but at lower concentration and frequency. So, site W6 seems tonbe contaminated by multiple sources, though mainly human. Finally, BacR was detected twice innPont d’Armes channel (W1), whereas HF183 was not detected. FRNAPH I and II were detectednin only 3 out of 12 water samples. Site W1 seems mainly contaminated by animal sources.nAs a result of our findings, actions were taken to remediate water and shellfish quality.