The Application of qPCR Assays for the Early Detection of Toxic Alexandrium in Eastern Australian Waters

Paralytic Shellfish Poison (PSP) is caused by naturally occurring marine biotoxins that are produced by some species of dinoflagellates. The marine Paralytic Shellfish Toxin (PST), which is associated to algal blooms, is a prevalent and persistent issue affecting shellfish harvesting areas around the world. The blooms have affected shellfish farms through closures and product recalls with losses of over $23 million. In addition, persistent symptoms are seen in about 2-3% of cases in humans and PSP is a potentially lethal clinical syndrome, which makes it an important health issue to address. In Australia, morphological species characterisations in important shellfish harvesting areas in Tasmania showed that toxic and non-toxic species of dinoflagellates are identical.  Formerly classified as Alexandrium tamarensespecies complex (A. catenellaA. pacificum, and A. australiense). Therefore, even though phytoplankton monitoring programs using light microscopy and High Performance Liquid Chromatography (HPLC) are in place, they do not give enough early warning to give farmer enough time to take management decisions. For this reason, we have developed a method of quantitative Polymerase Chain Reaction (qPCR) assays as an accurate and efficient on-farm early detection system. Our method can be used as well as a tool for long-term risk assessment will be outlined in this presentation. The assessment on the specificity, sensitivity and efficiency of rDNA-based assays and toxin gene (sxtA4)-based assay will be described, along with the efficacy of rDNA-based assay for cysts quantification to show their potential to be used as a long-term risk assessment tool for a new harvest area. Furthermore, the copy number variation of the target genes and their implications on cell quantification and toxin production will be discussed.


Rendy Ruvindy received his PhD (2019) from the Seafood Safety Group, Climate Change Cluster, The University of Technology Sydney. Prior to that, he was involved in start-up companies, when he decided to study a Masters in Biochemistry and Molecular Genetics, UNSW. His research interest lies in the use of current molecular techniques for microbial diversity characterisation, describing molecular mechanisms of toxin production in dinoflagellates and the ecological implications of marine toxins production. In addition to all these, he has been involved in training shellfish farmers in the early detection of PST, as he has been part of courses in NSW organized by the Seafood Safety Group lead by Prof. Shauna Murray.