碩士 / 國立臺灣海洋大學 / 食品科學系 / 93 / Blooms of the toxic, paralytic shellfish poisoning (PSP), chain-forming dinoflagellate Gymnodinium catenatum Graham pose a serious risk to human health, aquaculture developments and the coastal environment. G. catenatum was described for the fist time in Gulf of California, Mexico by Graham (1943). During the last 20 years, G. catenatum has been found in an increasing number of locations worldwide, e.g. Spain, Mexico, Japan, Portugal, Philippines, Uruguay, Morocco, Australia and China. The increasing number of reports has been attributed to coastal eutrophication, increasing scientific awareness, transportation by ship ballast water and currents, and global warming. In Taiwan, there have been two food poison incidents due to ingesting the purple clam in Taiwan, and the causative organism was identified as the toxic dinoflagellate Alexandrium minutum. The toxin production of the dinoflagellate A. minutum was affected by nutritional and environmental factors.The toxic dinoflagellate G. catenatum was kindly provided by Dr. Tamao Noguchi and cultured in modified f/2 medium. To investigate the best condition for cell growth and toxin production of G. catenatum, some environmental and nutritional factors of modified f/2medium were modulated. It was found that the optimal modified f/2medium conditions for G. catenatum were as follows: temperature 25~20℃, pH 5.5~7.5, light strength 120~ 240 μEm-2s-1, salinity 16~32‰, nitrate 75~750 ppm, phosphate 5~50 ppm, cupric ion 0.98 ppb, ferric ion 50 ppm and 2-20 ppm humic acid. Both cell toxicity and total toxicity reached the maximum level at the post-stationary growth phase and then decreased soon when the cells grew at the best condition. The toxic components of G. catenatum were extracted for toxin analysis by high performance liquid chromatography (HPLC), and found to contain C1 (epiGTX8) , C2 (GTX8), decarbamoyl gonyautoxin (dcGTX3) 3 and saxitoxin (STX),. Among these toxin components, toxins were the predominatant components throughout the growth cycle when the cells grew in the modified f/2 medium.
Electrolyzed oxidizing (EO) water has been reported by scientists in Japan to have strong bactericidal effects on most pathogenic bacteria. Major advantage of using EO water for inactivation of bacteria is that it is produced using pure water without adding chemicals except sodium chloride, thus no chemical survival, and no impact on biological organism and environment. To evaluate the effect of EO water on the growth and toxicity of the dinoflagellate G. catenatum, the different concentrations of EO water were added into the broth. It was found that EO water could completely kill G. catenatum when the concentration of EO water was over 5.0%. The concentration of 0.5% EO water only inhibited motility of dinoflagellate for several hours. Once G. catenatum solution was dealt with EO water and re-cultured, it was found that cell growth rate without EO water treatment were faster than that treated with EO water in the fist stage. The cell density was the same for 12 days among all groups. The maximam levels of cell and total toxicity for G. catenatum was found in the group without EO water treatment, and the level of toxicity decreased by the treatment of EO water on the algal broth. Moreover, toxicity decreased after treating with high concentration of EO water.
| Identifer | oai:union.ndltd.org:TW/093NTOU5253057 |
| Date | January 2005 |
| Creators | Ching Hsin Chiang, 江靜欣 |
| Contributors | Deng-Fwu Hwang, 黃登福 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 98 |
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