CHANGES IN DOMOIC ACID PRODUCTION AND CELLULAR CHEMICAL COMPOSITION OF THE TOXIGENIC DIATOM PSEUDO-NITZSCHIA MULTISERIES UNDER PHOSPHATE LIMITATION1

Authors

  • Youlian Pan,

    Corresponding author
    1. Habitat Ecology Section, Department of Fisheries and Oceans, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia, Canada B2Y 4A2
    2. Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1
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  • Durvasula V. Subba Rao,

    1. Habitat Ecology Section, Department of Fisheries and Oceans, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia, Canada B2Y 4A2
    2. Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1
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  • Kenneth H. Mann

    1. Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1
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  • 1

    Received 11 September 1995. Accepted 19 February 1996.

  • We thank Drs. J. E. Stewart and W. K. W. Li for the discussion of the work and for constructive criticism of the manuscript. We are indebted to the two anonymous reviewers for their expert criticism and constructive comments on the manuscript. We thank Dr. R. Pocklington and his associates who analyzed the domoic acid samples. This work was funded by a research grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) to K.H.M.

Present address and author for reprints: Institute of Marine Biosciences, National Research Council, 1411 Oxford Street, Halifax, Nova Scotia, Canada B3H 3Z1.

ABSTRACT

Production of domoic acid (DA), a neurotoxin, by the diatom Pseudo-nitzschia multiseries (previously Nitzschia pungens f. multiseries) Hasle and its cellular chemical composition were studied in phosphate-limited chemostat continuous cultures and in subsequent batch cultures. Under steady-state chemostat conditions, DA production increased from 0.01 to 0.26 pg DA · cell−1· d−1 as the growth rate decreased. When the nutrient supply was discontinued (to produce a batch culture), DA production was enhanced by a factor of ca. 3. DA production was temporarily suspended upon addition of phosphate to the batch cultures but resumed 1 d later at a higher rate coincident with the decline of phosphate uptake. In both steady-state continuous culture and batch culture, more DA was produced when alkaline phosphatase activity (APA) was high. The association of high DA production with high levels of APA and high cellular N:P ratios strongly suggests that phosphate limitation enhances DA production. Also, DA production was high when other primary metabolism (e.g. uptake of carbon, nitrogen, phosphorus and silicon, and cell division) was low, but chlorophyll a and adenosine triphosphate were generally high. This suggests that the synthesis of DA requires a substantial amount of biogenic energy.

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