• amnesic shellfish poisoning;
  • benthic diatom;
  • domoic acid;
  • Nitzschia sp;
  • Vietnam

Domoic acid (DA), a neuroexcitatory amino acid, was detected in batch culture of the newly recognized species Nitzschia navis-varingica Lundholm et Moestrup. The production of DA by this diatom was confirmed by electrospray ionization mass spectrometry. The diatom was collected from a shrimp-culture pond in Do Son, Vietnam. The production of DA (1.7 pg·cell1) is within the levels reported for Pseudo-nitzschia multiseries (Hasle) Hasle. The DA production started during the late exponential growth phase and reached a maximum during the early stationary growth phase. Maximum DA levels in the axenic culture decreased to about half that of the nonaxenic culture (0.9 pg·cell1 vs. 1.7 pg·cell1), suggesting that DA production by the new species is influenced by bacteria.