AWWA WQTC52931

None of the four main methods used to identify fecal sources has examinedvariation of the biomarkers over season. Differences among the biomarkers'occurrence in the E. coli population or amongst sampling sites have receivedlittle attention. Biomarker variation across waste collection methods on farms,the effects of herd size, or animal density are presently ignored. This workincluded the testing of samples from the farms in the US to determine theendemicity of the toxin gene biomarkers in E. coli populations among swine herdsfrom 7 states and cattle herds from 4 states. These farm samples were also usedto test the reliability of the human, cattle, and swine biomarker methods whichare polymerase chain reaction (PCR)-based and determine the fecal source bydetecting a species-specific sequence from the respective enterotoxin genes, STh,STII, and LTIIa. A five filter three dilution method was developed to estimatethe number of toxin positive E. coli within the total E. coli population. Includes 10 references, tables.