Towards Better Hygiene Standards: Detecting Fecal Contamination of Water Using Viral DNA

Scientists develop a new method to detect fecal contamination of water, paving the way towards healthier living environments globally

DAEJEON, South Korea, Dec. 26, 2024 /PRNewswire/ -- The presence of human waste in sewage overflow or stormwater runoffs that ultimately find their way into rivers and lakes is a major public health hazard. Conventionally, testing for fecal contamination involves detecting fecal indicator bacteria (FIB), such as E. coli. While FIB detection is cheap and simple, the method cannot be used to detect low-level contamination.

Microbial source tracking (MST) is a potential alternative which detects biomarkers—usually a protein or DNA segment—that are specific to a host species. This allows MST to detect low-level contamination in water bodies, and identify the source. CrAss-like phages (CLPs), a class of viruses that infect bacteria (bacteriophages), are being hailed as a promising group of MST markers. CLPs are the most abundant bacteriophages in the human gut, and many CLPs are only found in human intestines and feces. While there are several known groups of CLPs, only a single group, known as genus I, has been used as an MST marker.

Now, researchers from Chungnam National University, South Korea, in collaboration with Gyeongsang National University, developed a novel MST detection method using CLPs that was capable of specifically detecting human feces-contaminated water. The study was published in Volume 266 of Water Research on 15 Nov 2024 and made available online on 24 Aug 2024. "The primary aim of this study was to improve the efficacy and accuracy of detection methods used to assess specific fecal contamination. A robust MST marker would greatly help in our ability to mitigate health risks from fecal-contaminated water," said Dong Woo Kim.

To test the efficacy of this method, the researchers collected fecal samples from selected human volunteers. DNA extraction and sequencing was performed to detect and classify CLP viral genes. 13 distinct CLP groups were identified in human gut viruses, which were then used to develop specific markers for their detection via PCR. CLPs were found in 91.52% of human feces samples and were absent in all animal samples, except racoons. Of the 13 CLP groups classified identified, genus VI was present in 64.4% of samples, nearly double that of genus I (37.28%).

"Our method shows that genus VI is a potent MST marker in the Korean population. Using PCR to detect MHP genes of genus VI CLPs, or even genus I, can be a practical approach towards monitoring human fecal contamination of water," concludes Dr. Ok Kyung Koo.

In summary, CLPs, especially genus VI, could be used as viable MST markers capable of specifically detecting human fecal contamination. This is notable as human-specific MST markers can significantly impact hygiene regulations and lower public health costs.

Reference
Title of original paper: Development of a novel crAss-like phage detection method with a broad spectrum for microbial source tracking

Journal: Water Research

DOI: https://doi.org/10.1016/j.watres.2024.122330

About the institute
Chungnam National University (CNU), located in Daejeon, South Korea, is a leading national university renowned for its excellence in research and education. Established in 1952, CNU offers diverse programs in engineering, medicine, sciences, and the arts, fostering innovation and global collaboration. Situated near Daedeok Innopolis, a major R&D hub, it excels in biotechnology, materials science, and information technology. With a vibrant international community and cutting-edge facilities, CNU continues to drive academic and technological advancements, making it a top choice for students worldwide.
Website: https://plus.cnu.ac.kr/html/en/ 

Contact:
Gaeun Kim
+82 42-821-6239
[email protected]

SOURCE Chungnam National University