Evaluation of Different Methods for Detecting Male Specific Coliphages from Marine Water at Doheny Beach, CA
Public Deposited- Last Modified
- February 28, 2019
- Creator
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Tajuba, Julianne M.
- Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
- Abstract
- Male-specific (F+) coliphages, primarily F+ RNA coliphages, have been proposed as candidate indicators of enteric viruses in water. The purpose of the this study was to evaluate the use of F+ coliphages as viral indicators of fecal contamination in marine waters using: (1) the Coliphage Latex Agglutination and Typing (CLAT) immunoassay, a rapid and novel coliphage detection and typing method, (2) a rapid (5-hr) liquid culture enrichment, and (3) a standard overnight liquid culture enrichment method, EPA Method 1601, at Doheny Beach, CA. This study analyzed 75 1 L marine water samples following rapid enrichment and 101 samples following overnight enrichment. For both methods, samples were collected in 2007 and 2008. The study was continued for the summer of 2008 to better document the performance of modifications of the rapid coliphages methods that were intended to overcome deficiencies of the method identified in 2007. For samples collected in 2007 using the rapid-CLAT and the overnight-CLAT assay 3/75(4.00%) and 4/101(3.96%) samples were positive for F+ coliphages respectively. Higher detection rates were found by using rapid and overnight enrichment spot plating with 16/75(21.3%) and 27/101(26.7%), respectively. We tested the lysis zones of the spot plates for the presence of F+ coliphage with the CLAT and found that 16/101(15.8%) were positive for rapid and 23/101(22.7%) for overnight enrichments, respectively, both of which were significant increases in positivity (p<0.05). We analyzed the effect salinity has on the enrichment and found that by reducing the salt concentration of the seawater samples by adding 1-liter of salt-free water, the growth of E. coli and the propagation of coliphages was improved. E. coli growth during the rapid (5-hr) enrichment improved from 9.0x10^8 to 1.0x1O^9 cfu/mL and coliphage propagation improved from 2.3x10^5 to 1.0x10^6 pfu/mL. This dilution of seawater was used for the analysis of 75 samples in 2008. Using the rapid-CLAT and the overnight-CLAT assay 16/75 (21.3%) and 24/101(23.7%) samples were positive for F+ coliphages respectively in 2008. Following rapid and overnight enrichment spot plating we found 37/75(49.3%) and 76/101(75.2%) F+ coliphage-positive samples, respectively, which was significantly different by Fisher Exact Test analysis (p<005). The results of this study suggest that the CLAT assay needs further improvement to (1) increase coliphage virus detection in seawater enrichments or(2) reduce to a lower coliphage concentration the lower detection limit of the agglutination immunoassay as approaches to achieving maximum F+ coliphage detection.
- Date of publication
- May 2009
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- Simmons, Otto D.
- Sobsey, Mark
- Stewart, Jill
- Degree
- Master of Science in Public Health
- Academic concentration
- Environmental Health Sciences
- Degree granting institution
- University of North Carolina at Chapel Hill
- Graduation year
- 2009
- Language
- Deposit record
- e00f1df6-6c31-41ba-867b-150d86a8c8cb
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