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: The tuf gene was amplified from samples enriched for enterococci and separated using DGGE (Fig. 4). The signature for enterococci was less complex than for E. coli and reasonably informative. The Larrakeyah sewage outfall (site 27) had a similar enterococci community profile to nearby beaches at Doctors Gully (site 28) and Lameroo Beach (site 29), while the enterococci community from the Leanyer-Sanderson sewage outfall (site 1) did not match nearby beaches (site 2) and replicate samples from this outfall were variable. The third sewage outfall (Ludmilla; site 14) had no profile because no colonies grew on the enterococci-specific media plates, probably due to the chlorine gas treatment at this plant. Sites in the lower reaches of Rapid Creek (sites 6–9) had a similar profile to each other, and Mindil Beach (sites 23 and 24) were similar to several nearby creeks and drains (sites 21 and 22). The distinct geographical groupings of the enterococci community profiles, i.e., Larrakeyah (sites 27–29), Mindil Beach (sites 21–24) and lower Rapid Creek (sites 6–9), resemble the clusters of high bacterial counts in Table 1 and Figure 3.
Affiliation: Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia.