THREE NEW KINDS OF TOXIC PSEUDO-NITZSCHIA SPECIES DERIVED FROM CHINA’S COAST

In order to investigate the diversity of Pseudo-nitzschia species in China’s coast and their ability in producing neurotoxin domoic acid (DA), a total of fifteen monoclonal Pseudo-nitzschia strains were isolated and established. Using a liquid chromatography tandem-mass spectrometry (LC-MS/MS) technique, DA was accordingly detected from ten monoclonal strains. Based on the morphology observed by using a light microscope (LM), a transmission electron microscope (TEM), as well as molecular analysis inferred from an internal transcribed spacer region, these fifteen strains were precisely identified which belonged to three different species involving, P. cuspidata (Hasle) Hasle, P. pseudodelicatissima (Hasle) Hasle, and P. fraudulenta(Cleve) Hasle. In addition, three out of eleven established P. cuspidata strains were nontoxic, while other eight cases were toxic with the DA abundance rate of 0.4—5.5 fg/cell. Also, one P. pseudodelicatissima strain was nontoxic, while DA production rate of 1 fg/cell was detected in another strain. Besides, no DA was tested in the two P. fraudulenta strains. Several strains were selected and their DA productions were induced by the available Artemia salina. As a result, it was shown that the ability of DA production decreased in P. cuspidate (MC4049) and P. pseudodelicatissima (MC3015) strains, from 2 and 1 to 0.2 and 0.4 fg/cell, respectively. However, the ability of DA production in P. fraudulenta(MC4074) strain swiftly increased, from an undetected level to 17.5 fg/cell. The results achieved in this study enrich the diversity of toxic Pseudo-nitzschiaspecies in China’s coast, and may establish strong research basis for conducting further studies.