碩士 / 元智大學 / 生物科技暨生物資訊研究所 / 96 / A halophilic bacterium isolated from a salt environment located in southern Taiwan was identified as a Marinococcus sp. The bacterium could synthesize and accumulate intracellular ectoine as a compatible solute to resist osmotic stress in a hyper-osmotic environment. The chemical structure and molecular mass of the purified product was confirmed by 13C-NMR, 1H-NMR, and FAB-MS. The fermentation medium composition was optimized via response surface methodology (RSM) to improve ectoine production from Marinococcus sp. With the optimization strategy, the ectoine production was enhanced from 0.6 g/L to 3.5g/L.
Subsequently, in order to break through the ectoine production, so use the different fermentation strategies. First, ectoine accumulated by Marinococcus sp. to cope with hyperosmotic pressure environment, interested, the ectoine are released from the microorganisms when they are exposed to osmotic downshock. Via this characteristic, in this study developed a continue extracted fermentation strategy and the ectoine productivity was advance to 3.0 g/L/Day; in addition, the ectoine concentration even reach to 7.0 g/L when Marinococcus sp. incubated for 93 hours through the repeat-batch fermentation strategy. So combine the continue extracted fermentation strategy and repeat-batch fermentation strategy, the result was amazingly. In the two stage fermentation strategy, the maximum ectoine concentration was not only reached to 6.0 g/L but also the ectoine productivity was more than 10.0 g/L/Day. By the way, although the Marinococcus sp. incubated for a long time and extracted repeatedly but the microorganisms still maintain the ability of ectoine produce, and it is an advantage for the ectoine production.
Finally, to achieve a large scale of supply for ectoine in compliance with the demands, the 5 L fermentor has been used. The results show that ectoine concentration, content and productivity can reach to 3.3 g/L, 11% and 2.6 g/L/Day when the Marinococcus sp. incubated for 30 hours, respectively. Moreover, the ectoine concentration and productivity even reach to 5.6 g/L and 3.9 g/L/Day via the fed-batch fermentation strategy, which the feed timing of yeast extract was depended on pH and DO factors.
The ectoine production by Marinococcus sp. has successes development in this study. Where the maximum ectoine concentration was reach to 7.0 g/L as well as the ectoine productivity even more than 10.0 g/L/Day through the different fermentation strategies in flask cultured. In addition, the ectoine concentration and productivity were also reaching to 5.6 g/L and 3.9 g/L/Day. Especially, the maximum ectoine productivity in this study was the highest in the ectoine production field.
| Identifer | oai:union.ndltd.org:TW/096YZU05111001 |
| Date | January 2008 |
| Creators | Fang-Wei Yuan, 袁芳偉 |
| Contributors | 魏毓宏 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 86 |
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