Diatom Nitzschia navis-varingica (Bacillariophyceae) and its domoic acid production from the mangrove environments of Malaysia

Tan SN 1 , Teng ST 2 , Lim HC 3 , Kotaki Y 4 , Bates SS 5 , Leaw CP 6 Show all authors , Lim PT 7

Affiliations 

  • 1 Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
  • 2 Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
  • 3 Tunku Abdul Rahman University College, Johor Branch, 85000 Segamat, Johor, Malaysia
  • 4 School of Marine Biosciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
  • 5 Fisheries and Oceans Canada, Gulf Fisheries Centre, P. O. Box 5030, Moncton, New Brunswick E1C 9B6, Canada
  • 6 Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia. Electronic address: cpleaw@um.edu.my
  • 7 Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia. Electronic address: ptlim@um.edu.my
Harmful Algae, 2016 12;60:139-149.
PMID: 28073557 DOI: 10.1016/j.hal.2016.11.003

Abstract

The distribution of the toxic pennate diatom Nitzschia was investigated at four mangrove areas along the coastal brackish waters of Peninsular Malaysia. Eighty-two strains of N. navis-varingica were isolated and established, and their identity confirmed morphologically and molecularly. Frustule morphological characteristics of the strains examined are identical to previously identified N. navis-varingica, but with a sightly higher density of the number of areolae per 1μm (4-7 areolae). Both LSU and ITS rDNAs phylogenetic trees clustered all strains in the N. navis-varingica clade, with high sequence homogeneity in the LSU rDNA (0-0.3%), while the intraspecific divergences in the ITS2 data set reached up to 7.4%. Domoic acid (DA) and its geometrical isomers, isodomoic A (IA) and isodomoic B (IB), were detected in cultures of N. navis-varingica by FMOC-LC-FLD, and subsequently confirmed by LC-MS/MS, with selected ion monitoring (SIM) and multiple reaction monitoring (MRM) runs. DA contents ranged between 0.37 and 11.06pgcell-1. This study demonstrated that the toxigenic euryhaline diatom N. navis-varingica is widely distributed in Malaysian mangrove swamps, suggesting the risk of amnesic shellfish poisoning and the possibility of DA contamination in the mangrove-related fisheries products.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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