title: A biomarker for the identification of cattle fecal pollution in water using the LTIIa toxin gene from enterotoxigenic Escherichia coli.
abstract: This research describes a method based on PCR to identify cattle fecal pollution in water using a portion of the heat labile toxin IIA (LTIIa) gene from enterotoxigenic Escherichia coli (ETEC). We describe the development of the primers and target. DNA extracts (221) from different animal fecal and human sewage samples were screened and showed no cross-reactivity. Minimum detection limits using centrifugation and filtration methods to concentrate E. coli seeded into stream, ocean, and secondary effluent waters were found to be at femtogram and attogram levels, respectively. Stability of the biomarker in stream, ocean, and secondary effluent waters was 2-4 weeks for all water types. Finally, 33 farm lagoon and waste samples were collected and 31 tested to validate the method; 93% were positive for the LTIIa trait when >1,000 E. coli were screened and 100% positive when >10(5) E. coli were screened. Prevalence of the toxin gene in the E. coli population affected the outcome of the analyses. The cow biomarker can be used in watershed studies to identify cattle waste with great accuracy if the appropriate numbers of E. coli are screened.
authors.affiliation: Department of Environmental Analysis and Design, 1368 Social Ecology II, University of California, Irvine, CA 92697, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Khatib
authors.forename: Y L
authors.initials: YL
authors.lastname: Tsai
authors.forename: B H
authors.initials: BH
authors.lastname: Olson
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics*; D015415:Biomarkers; D002417:Cattle / Q000382:microbiology*; D017931:DNA Primers; D004768:Enterotoxins / Q000235:genetics*; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D029968:Escherichia coli Proteins; D005243:Feces / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014876:Water Pollution
chemical_list: D001427:Bacterial Toxins; D015415:Biomarkers; D017931:DNA Primers; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C027538:heat-labile enterotoxin, E coli