S. M. Haque, Y. Onoue
Effects of Salinity on Growth and Toxin Production of a Noxious Phytoflagellate,
Heterosigma akashiwo (Raphidophyceae)
Growth and toxin production of a noxious phytoflagellate Heterosigma akashiwo (Kagoshima strain) were investigated at a salinity range from 20–40?. The maximum growth (0.68 ± 0.03 divisions day?1) was obtained at 25?, while the lowest growth (0.48 ± 0.02 divisions day?1) was attained at 40?. The lower salinity was found suitable for maintaining a better morphological condition and motility of the cells. The Kagoshima strain became more toxic at 20?, and the toxicity decreased with increased salinity. A negative correlation between salinity increase and toxin production was found on HPLC analysis of H. akashiwo toxins (HaTx-I, II, III and IV). Toxin HaTx-IV (corresponding to oxidized PbTx-2) was most dominant and peaked at 20? with a yield of 0.3 pg cell?1. Considerable amounts of HaTx-I and III (corresponding to PbTx-2 and 3) were also detected. However, HaTx-II (corresponding to PbTx-9) was detected only as a trace at 20 and 25?. A sharp decrease in all toxins was found at salinities above 30?. The increase of specific growth rate raised the toxin content per cell of the strain.
Botanica Marina, Walter de Gruyter
Print ISSN: 0006-8055
Volume: 45, 07/2002
Pages: 356 - 363
Show full article (external site)
Show all available items of this journal
Search
