碩士 / 國立海洋大學 / 食品科學系 / 87 / Abstract
The toxic dinoflagellate Alexandrium minutum was isolated from southern Taiwan and cultured in modified K medium. To find the best condition for cell growth and toxin production of A. minutum, some environmental and nutritional factors of modified K medium were modulated. It was found that the optimal environmental and nutritional conditions for those of A. minutum were as follows: temperature 25 oC, pH 7.5, light strength 6000 Lux, salinity 15 ppt, nitrate 0.01%, phosphate 0.002%, cupric ion 5.0 ppb, ferric ion 270 ppb and humic acid free. Both cell toxicity and total toxicity reached the maximum level at the post-stationary growth phase and then decrease soon when the cells were grown at the best condition. The toxic components of A. minutum were assayed by high performance liquid chromatography, and found to contain gonyautoxin (GTX) 1-4 only. Among these toxin components, toxins GTX1,4 were the predominatant components throughout the growth circle when the cells were grown in the modified K medium. While the algae grown under the condition of high temperature (30 oC), high salinity (22.5-30 ppt) and high light strengh (1,2000 Lux), the amount of toxins GTX2,3 was found to increase.
Although it is generally considered that PSP is associated with dinoflagellates, such as A. minutum, it has been suggested that heterotrophic bacteria may be responsible for toxin synthesis in these organisms. The symbiotic bacteria of A. minutum were isolated and identified as follows: extracelullar species including Pasteurella haemolytica, Sphmon pancimobilis and Pseudomonas vesicularis, and intercelullar species including Pasteurella pneumotropica, Morganella wisconsensis, Flavobacterium oryzihabitans, Pseudomonas pseudomallei and Sphmon pancimobilis. All of them were cultured and determined to have no PSP-producing ability identified by HPLC analysis. The cell toxicity of A. minutum did not decrease even the culture medium were added with antibiotics. When the dinoflagellate were cultured together with symbiotic bacteria, M. wisconsensis, S. pancimobilis or P. pseudomallei the growth of A. minutum was better than that with no bacteria at the beginning, but the maximun cell number was lower. The cell toxicity of A. minutum cultured with bacteria was similar to that of A. minutum cultured without bacteria from lag phase to stationary phase, but it is lower after stationary phase.
| Identifer | oai:union.ndltd.org:TW/087NTOU0253033 |
| Date | January 1999 |
| Creators | Lu Ya Hui, 呂雅蕙 |
| Contributors | Hwang Deng Fwu, 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 | 85 |
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