Changes in toxins, intracellular and dissolved free aminoacids of the toxic dinoflagellate Gymnodinium catenatum in response to changes in inorganic nutrients and salinity
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AuthorsFlynn, K.J. (Kevin); Flynn, K. (Krystyna); John, E.H. (Eurgain); Reguera, B. (Beatriz); Reyero, M.I. (Isabel); Franco, J.M. (José Mariano)
The paralytic shellfish poison prducing dinoflagellate Gymnodiniun catemrum was subjected to changes in salinity, phosphate, ammonium and nitrate using continuous culture and batch culture methods. In contrast with other algae, this species showed very slow changes in the concentration of intracellular amino acids, in the Gln:Glu ratio, and, in contrast with Alrsandnum spp., only slow changes in toxin content, during such events as N-feeding of Ndeprived cells or during nutrient deprivation. This organism was found to be very susceptible to disturbance; maximum growth rates around 0.25–0.3 day−1 with a minimum C:N mass ratio of 5.5, were attained when cultures were only disturbed by sampling once a day. P-deprived cells were larger (twice the usual C content of 4 ng C cell−1 and volume of 20 pl). The content of free amino acids was always low (5% of cell-N), with low contributions made by arginine (the precursor for paralytic shellfish toxins). Cells growing using ammonium had the lowest ...