Rapid detection of toxic dinoflagellate, Alexandrium minutimi (dinophyceae) using fluorescence in situ hybridization (FISH)

Abstract

Harmful algal blooms (HABs) are phenomena known as sudden increase in Microalgal population that cause seafood poisoning in human and impact to marine ecosystem. Dinoflagellates from the genus Alexandrium had been known to be responsible for paralytic shellfish poisoning (PSP) toxins with the production of sodium blocking neurotoxins collectively called saxitoxin (STX). Species identification in thisgenus is based on thecal plate tabulation and minute morphological character, which is often hard to observe during regular plankton monitoring that require taxonomic expertise. Hence, a molecular detection approach using whole-cell fluorescence in situ hybridization (FISH) was investigated in this study for the rapid detection of Alexandrium. Ribosomal DNA probes targeting the toxic A.minutum were designed in silico. Specificity and accessibility of designed probes were further verified in silico by comparing parameters that influenced hybridization kinetics. Species-specific probe which was designated as L-S-Amin-569-A-18 was synthesized and optimized using the clonal cultures of A minutum. The results showed that the DNA probe had high specificity towards A minutum, with no cross-reactivity towards other Alexandrium species. The whole-cell FISH coupled with the species-specific probe showed its potency as a rapid detection tool of A. minutum in Malaysian waters.which could be adopted in the national harmful algal monitoring program.