In many aquatic ecosystems world-wide, including drinking water supplies, cyanobacteria and dinoflagellates can proliferate into the so-called harmful algal blooms (HAB). Members of these microbial phyla can produce an unparalleled array of bioactive secondary metabolites; some of which are potent toxins. The past ten years has witnessed major advances in our understanding of the genetic basis for toxin production by a number of groups of these microorganisms.
Genomic information related to toxin synthesis has also indicated their environmental and cellular regulators, as well as associated transport mechanisms. The information gained from the discovery of these toxin biosynthetic pathways has also enabled the genetic screening of various environments for drinking water and seafood quality management.
Cyanobacteria toxins are produced by many strains of cyanobacteria spanning multiple genera, however, as toxicity is not uniform among strains, conventional bacteriological classification methods are unable to accurately predict toxicity and analytical methods for the detection of the toxins often take days to perform and are not predictive. It has long since been realized that early detection methods for toxic cyanobacteria are critical as the consumption of cyanotoxins can lead to a myriad of serious health effects and can be fatal in high doses.
The synthesis of saxitoxin in dinoflagellates occupying marine environments has been recently found to be catalysed by a group of enzymes encoded by sxt genes, beginning with the unusual gene, sxtA. A quantitative PCR assay targeting sxtA gene to detect saxitoxin-producing dinoflagellates in marine environmental samples is being developed for use in marine environment management. The abundance of sxtA correlates with the abundance of the saxitoxin-producing species of such as Alexandrium species. Using this assay, detection and quantification of sxtA in HAB events in Australia and New Zealand has been correlated with saxitoxin uptake in shellfish.
Diagnostic Technology is developing and validating a molecular based test for the detection of cyanotoxin production in fresh, brackish and marine water environments, that pose a direct threat to public health. The CyanoDTec is a simple molecular assay for the simultaneous detection of hepatotoxins such as microcystin, nodularin and cylindrospermopsin and neurotoxins such as saxitoxin.