Exploring Fecal Bacterial Diversity for Microbial Source Tracking by Barcoded Pyrosequencing

Faecal bacteria communities of humans and animals for the microbial source tracking purpose were explored by using bacrcoded pyrosequencing. Total 56,372 of 16S rRNA pyrosequencing reads were obtained from feces of humans and animals. Cluster profiling of the relative abundance in each taxon showed each fecal sample was not distinguishable at divisions of phylum, class, and order. Under division family, sequence divergence in the 5 commonly identified taxa (family Lachnospiraceae, Porphyromonadaceae, and Veillonellaceae, and genus Lachnospiraceae_uc and Ruminococcaceae_uc, respectively) showed host specificity to poultry, dairy cattle, human, duck-goose, and cattle-swine, respectively. Whole sequence divergence in phylum Bacteroidetes, Firmicutes, and Proteobacteria were respectively examined to compare fecal samples against two freshwater samples (Y1, and Y2) from Yeongsan river, Jenonnam Province, Korea. The 5 commonly identified taxa were also used to track the source of fecal bacteria in Y1 and Y2 sites. Furthermore, we developed one simple measurement by scoring each pyrosequencing read shared between feces and environment. All three methods indicated that human and swine are likely to be the potential fecal source in the Y1 site and no specific source was identified for the Y2 site. Our results suggest the high possibility in using pyrosequencing for microbial source tacking.