Water Science & Technology—WST Vol 61 No 1 pp 1–7 © IWA Publishing 2010 doi:10.2166/wst.2010.767

Application of mitochondrial DNA analysis for microbial source tracking purposes in shellfish harvesting waters

Craig Baker-Austin, Rachel Rangdale, James Lowther and David N. Lees

We present a method for the reliable detection and source characterisation of faecal pollution in water and shellfish matrices, utilising real-time PCR analysis of mitochondrial DNA targets. In this study we designed real-time PCR (TaqMan) probes to target human, bovine, ovine and swine mtDNA. PCR amplification using species-specific TaqMan probes on faecal matter and mixed effluent slurries revealed no cross-reactions between species of interest and other vertebrate faecal matter. Performed as a single blind experiment we were able to correctly identify faecal material in 17/20 effluents (85% correct). mtDNA degrades relatively quickly in faecally-spiked water samples (~2 weeks), a similar timeframe of environmental persistence to several bacterial faecal indictors, highlighting its applicability. The procedure described here is specific, rapid (<5 hours) and sensitive. These results confirm the suitability of using species-specific mtDNA as an indicator in source tracking studies in surface waters, shellfish harvesting areas and shellfish matrices.

Keywords: faecal contamination; mitochondrial DNA; shellfish; TaqMan

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