PREDICTING SOURCES OF FECAL POLLUTION USING FATTY ACID METHYL ESTER (FAME) PROFILING

The objective of this study was to test the efficacy of host-specific fatty acid methyl ester (FAME) profiles of total coliform (TC) and fecal coliform (FC) to predict sources of fecal pollution in water environments. A total of 96 samples are collected and a known-source FAME library consists of 314 FC and 303 TC was constructed. Additionally, five water samples were collected from a natural pond at a public park near Villanova, PA and 37 FC isolates were cultured. The FAME profiles of these isolates were compared to the FAME profiles those in the known-source library. Isolates in the known-source library were cultured from; sewage for the human category; stool samples of bovine, poultry, and swine for the livestock category; and stool samples of deer and Canada geese for the wildlife category. It was found that hydroxy FAMEs were exclusively associated with isolates of human origin. On the other hand, three saturated FAMEs and a branched FAME were found only in isolates from non-human sources. In addition, the FAME profiles of the isolates in the known-source library showed statistically significant host specific differences in terms of the average relative masses of particularly the unsaturated FAMEs. A linear discriminant function based on the FAME profiles of know-source isolates was used to predict the source of the isolates cultured from the pond samples and 30 of 37 FC fecal isolates were classified as wildlife. Considering that the pond had a large population of Canada geese and there was no other apparent source of fecal matter, these classifications were considered highly accurate. The results show that the FAME profiles of FC isolates show statistically significant host specificity and have the potential to be used as a phenotypic microbial source tracking (MST) tool.