Multiple approaches to microbial source tracking in tropical northern Australia.
Bottom Line: To address this, we sampled sewage outfalls, other potential inputs, such as urban rivers and drains, and surrounding beaches, and used genetic fingerprints from E. coli and enterococci communities, fecal markers and 454 pyrosequencing to track contamination sources.Two other treated effluent discharges did not appear to influence sites other than those directly adjacent.Generally, connectivity between the sites was observed within distinct geographical locations and it appeared that most of the bacterial contamination on Darwin beaches was confined to local sources.
Affiliation: Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia.Show MeSH
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Mentions: All of the beach sites had numerous OTUs in common, and they were also similar to many of the “other input” sites, Lake Alexander and lower Rapid Creek (Figs. 6A and 7). The upper reaches of Rapid Creek (sites 10, 11, and 12) were freshwater sites (Table S2) and their microbial communities were, not surprisingly, different (Fig. 6). Interestingly, two of the sewage outfalls had many OTUs in common with each other (sites 14 and 27) but the third site was different (site 1). This reflects the nutrient profiles of the outfalls (Table S3), in which nutrients were more similar at sites 14 and 27 compared to site 1. Although the differences were likely related to the various treatment processes used at the outfalls (see Experimental Procedures for description), the specific reason for this discrepancy is unclear. At the phylum level, most of the sites were dominated by members of the Proteobacteria, except for the two similar outfalls (sites 14 and 27), which contained many Firmicutes bacteria (Fig. 6B).
Affiliation: Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia.