碩士 / 國立臺灣海洋大學 / 食品科學系 / 92 / Abstract
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 A. catenella was belonged to Alexandrium spp. and had usually been reported in cold waters in several regions of the world. However, outbreaks of A. catenella has recently reported in temperate and subtropical regions. The toxic dinoflagellate A. catenella was kindly provided by Dr. Tamao Noguchi and cultured in modified SWM-3 medium. To investigate the best condition for cell growth and toxin production of A. catenella, some environmental and nutritional factors of modified SWM-3 medium were modulated. It was found that the optimal modified SWM-3 medium conditions for A. catenella were as follows: temperature 25℃, pH 7.5, light strength 120 μEm-2s-1, salinity 23.5 ppt, nitrate 0.017%, phosphate 0.0016%, cupric ion 0.64 ppb, ferric ion 103 ppb and non for 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 A. catenella were extracted for toxin analysis by high performance liquid chromatography (HPLC), and found to contain gonyautoxin (GTX) 1-5, neosaxitoxin (neoSTX), C1 (epiGTX8) and C2 (GTX8). Among these toxin components, toxins GTX1 and 4 were the predominatant components throughout the growth cycle when the cells grew in the modified SWM-3 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 A. catenella, the different concentrations of EO water were added into the broth. It was found that EO water could completely kill A. catenella when the concentration of EO water was over 1.0%. The concentration of 0.5% EO water only inhibited motility of dinoflagellate for several hours. Free available chlorine (FAC) but not pH and oxidation-reduction potential (ORP) of EO water could kill A. catenella. Once A. catenella 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 A. catenella 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, C1, C2, GTX3 and GTX2 increased while GTX1 and GTX4 decreased after treating with high concentration of EO water.
| Identifer | oai:union.ndltd.org:TW/092NTOU5253033 |
| Date | January 2004 |
| Creators | Chin-Hua Hung, 洪金樺 |
| Contributors | Deng-Fu 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 | 91 |
Page generated in 0.0021 seconds