Detection of Gambierdiscus and Fukuyoa single cells using recombinase polymerase amplification combined with a sandwich hybridization assay

Dinoflagellates of the genera Gambierdiscus and Fukuyoa are known to produce several bioactive compounds including the potent neurotoxic ciguatoxins (CTXs) which are able to accumulate in fish and through the food web. When humans ingest fish contaminated with CTXs, it can result in an intoxication named ciguatera. Although not all the currently recognized species are able to produce toxins, G. australes and G. excentricus have been highlighted to be the most abundant and toxic among the species present in the Atlantic. Even though the genera Gambierdiscus and Fukuyoa are endemic to tropical areas, recently their presence was recorded in subtropical and temperate regions. In this work, the development of three molecular assays for the detection of the Gambierdiscus and Fukuyoa genera and for G. australes and G. excentricus species, based on the combination of recombinase polymerase amplification with detection via hybridization, is successfully described. Furthermore, a remarkable limit of detection of a single cell was achieved. Additionally, six different species have been used to check the ability of each primer set to give an amplified product, even in presence of potentially interfering non-target DNAs. Therefore, these developments provide a rapid and cost-effective strategy for detection of both genera and two of the most toxic species, which will undoubtedly contribute to reliable screening of samples and ciguatera risk assessment, guaranteeing seafood safety and protection of human health.