MICROBIAL SOURCE TRACKING TO IDENTIFY FECAL POLLUTION IN RECREATIONAL WATERS FROM THE WIERNA AND MOJOTORO RIVERS IN SALTA, ARGENTINA

REYES, SARITA ISABEL; SAID ADAMO, MARÍA DEL MILAGRO; POMA, RAMIRO HUGO; RAJAL, VERÓNICA BEATRIZ; CRISTÓBAL, HÉCTOR ANTONIO

Salta

Congreso; PABMB SAIB 2019; 2019

SAIB

The presence of fecal pollution in environmental waters, coming from wastewater treatment plant and illegal discharges, and runoff of animal feces, represents a threat to human health and an environmental concern all around the globe. The microbiological water quality is traditionally assessed by enumerating fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli and Enterococcus). Although these FIB are employed in the world, these indicators do not accurately predict the health risk of other human pathogens. Nevertheless, microbial source tracking (MST) methods, based in the determination of genetic markers from bacteroides (bacteria found in the gastrointestinal tracts of warm-blooded organisms), can discriminate between human or animal fecal pollution sources. The main of this study was to identify the origin and magnitude of fecal pollution by detecting universal, human and bovine Bacteroides in water samples from the Wierna and Mojotoro rivers, at the Province of Salta, Argentina. Water samples were obtained from thee points (P): P1 at Wierna river, where recreational activities develop, and P2 and P3 from Mojotoro river, which receives the discharges of two wastewater treatment plants (one inactive and the other currently operating). A total of 30 20-l water samples were collected from each point and concentrated by ultrafiltration to a final volume of approximately 50 ml. DNA extractions were performed from the concentrates and real-time PCR assays were carried out to detect 16S rDNA from Bacteroides. Universal (using BacUni oligonucleotides), human (with BacHum) and cow (with BacRum) markers were determined by duplicate. The universal marker was found in all the sites evaluated in a concentration range from 6.10 x101to 7.71 x103 genomic copies per ml. The human marker was found in a concentration range from 5.44 x102 to 7.22 x103 genomic copies per ml. however, the ruminant marker was found in less proportion in the samples analyzed. The outcome confirmed the existence of fecal contamination of human origin, which represents a health risk to people who use these rivers for recreational purposes. In conclusion the results highlight the importance of intensifying studies that contribute to improve the assessment of water quality using alternative strategies.