碩士 / 國立中興大學 / 生物產業機電工程學系所 / 98 / The purpose of this study is to investigate light factors about microalgal reproduction, lipid content and relations of fatty acid compositions in microalgal cultivation. The different tests include in light quality factor tests, optimal light factor tests, light change tests and optimal light change tests. Light quality factor tests used Nannochloropsis oculata to test 48 hours in exponential reproduction period, and used blue light(455~480nm), white light(400~700nm) and red light(625~690nm) to proceed the tests. The experimental results showed obvious influence of microalgal reproduction, oil content and relations of fatty acid compositions in light quality. The experimental results found the red light group to have the best result in reproduction which was up to the initial microalgal cells density of 2.5 times. The white light group was 1.75 times and the worst was the blue light group of 1.6 times only. The result of the revealed a rapid decrease of the lipid content of unit cell in the red light group, lipid content experiment while the white light group, and the blue light group could maintain more lipid content. The results had shown the reproduction of the microalgae grew faster and unit lipid content decreased in exponential reproduction period. Light quality to microalgae of fatty acid compositions results presented the red light group was better on saturated fatty acid of C16:0 and unsaturated fatty acids of C18:2n6. Besides, the blue light group was better on unsaturated fatty acids of C16:1n7, C18:1n9, C18:3n3 and C20:5n3. The white light group did not affect the fatty acid compositions.
The optimal light factor tests used on orthogonal array L9(34) were done using the Taiguchi Method to choose light factors of environment, which include light quality, light intensity, initial cells density and light period to obtain the optimization of microalgal reproduction, lipid content and fatty acid compositions. The optimization result revealed that due to red light, light intensity 2,000lux, initial density 1,000×104 cells/ml and light period 24/0 hr(light/dark), the microalgal reproduction was the best. The optimal unit lipid content used blue light, light intensity 2,000lux, initial density 2,000×104 cells/ml and light period 8/16 hr. The test resulted to optimal content condition of fatty acid compositions；it could divide into two parts of red light C16:0, C18:2n6 and blue light C16:1n7, C18:1n9, C18:3n3, C20:5n3, respectively. The best content of EPA-C20:5n3 could be via blue light, light intensity 1,000lux, initial density 2,000×104 cells/ml and light period 8/16 hr to get.
The results of light change proved that the microalgae turned into other light quality environment from origin light quality environment in cultivation, microalgal cells had trend to change with microalgal cells reproduction, microalgal cells lipid content and fatty acid compositions. After 48 hours, the test changed from blue light cultivation to red light cultivation and kept cultivation to 72 hours, the microalgal cells density originally of 1511±93.4×104 in 48 hours increased to 2401±78.3×104 cells/ml in 72 hours. It was 1.29 times higher than the unchanged light cells density 1865±54.5×104 cells/ml in 72 hours. However, the unit lipid content originally of 21.3±0.58% in 48 hours decreased to 14.5±0.48% in 72 hours, and it was 1.15 times lower than the of unchanged light unit lipid content 16.8±0.77%. It showed that the content of unsaturated fatty acid EPA-C20:5n3 arrived at 3.23±1.00%, and was 2.13 times lower than the unchanged light content 6.87±0.53%. Besides, the test changed from red light cultivation in 48 hours to blue light cultivation and kept cultivation to 72 hours, the microalgal cells density originally of 1788±70.3×104 in 48 hours increased to 1990±104.9×104 cells/ml in 72 hours. It was 1.28 times lower than the unchanged light cells density 2542±86.8×104 cells/ml, while the unit lipid content originally of 17.9±0.85% in 48 hours decreased to 15.1±0.37% in 72 hours as 1.29 times higher than the unchanged light unit lipid content 11.7±0.92% in 72 hours. It also showed that the content of unsaturated fatty acid EPA-C20:5n3 arrived at 4.41±0.49%, and was 2.25 times higher than the unchanged light content 1.96±0.73%. The results had shown the method of change light quality could control microalgal cells density, microalgal unit lipid content and fatty acid compositions effectively, and could reach optimal content of microalgal cells density, lipid content and fatty acid compositions. The results presented here show the relations of light factors cultivation parameters, and it supports a principle and effective microalgae control using the cultivation bioreactor in the future.Moreover, the relations of light factors cultivation parameters can not only increase the cultivation density but also raise microalgal lipid content and value of fatty acid compositions.
| Identifer | oai:union.ndltd.org:TW/098NCHU5415020 |
| Date | January 2010 |
| Creators | Hsin-Hsien Lu, 呂信賢 |
| Contributors | 尤瓊琦 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 134 |
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