碩士 / 國立交通大學 / 分子醫學與生物工程研究所 / 99 / In recent years, due to global warming and energy crisis, the low-polluted and renewable microalgal bioenergy industry is of great concern. How to improve the development of microalgal energy to achieve maximum beneficial result is the major goal all over the world. In this research, Chlorella sp. with high growth rate and Nannochloropsis oculata with high lipid content were selected as potential strains. In addition, two phase cultivation strategy was applied to enhance lipid production. In long-term phototrophic cultivation, maximum lipid content of Chlorella sp. and N. oculata can reach 42.6% and 66.1%, respectively. The lipid production of Chlorella sp. and N. oculata can reach 0.38 g/L and 0.78 g/L on the 20th day, respectively. In the two phase cultivation strategy, microalgae phototrophically grew and reached stationary phase as the first phase (8 days) cultivation for microalgal biomass production. The following 3 days of mixotrophic or heterotrophic cultivation after the first phase in the presence of either glucose, sucrose or molasses was as the second phase cultivation. The microalgal culture aerated with only CO2-enriched gas in the second cultivation phase was as the control experiment. The purpose of the second cultivation phase (3 days) was for enhancing the microalgal lipid accumulation or altering the lipid compsitions.
In this study, the lipid production of indoor cultivation of Chlorella sp. which used sucrose as carbon source in mixotrophic cultivation can increase the lipid content to 41.4% and the lipid production was 0.53 g/L. There were similar results that the highest lipid content (60.6%) and lipid production (0.81 g/L) of N. oculata using sucrose as carbon source. Therefore, we demonstrated that Chlorella sp. and N. oculata are light-dependent for organic carbon source uptake and the two microalgal strains can not culture in heterotrophic mode while use either glucose, sucrose or molasses as carbon source. Chlorella sp. and N. oculata can culture by mixotrophic two phase cultivation strategy for increasing microalgal biomass and enhancing the lipid production in short time (3 days) without altering the lipid compsitions.
In outdoor two phase cultivation, Chlorella sp. cultured outdoors during the first phase (8 days) followed by indoor cultivation (3 days) in mixotrophic or heterotrophic mode in the presence of either glucose, sucrose or molasses. The lipid content and lipid production of Chlorella sp. using glucose as carbon source can reach 24.3% and 0.26 g/L after the second phase mixotrophic cuitivation., The lipid production of Chlorella sp. using glucose as carbon source by two phase mixotrophic cultivation strategy can increase almost 2folds compared with the lipid production of outdoor long-term photoautotrophic cultivation of Chlorella sp.. Thus, microalgae culture by the two phase cultivation strategy, outdoor photoautotrophic cultivation (8 days) as the first phase combined with indoor mixotrophic cultivation (3 days) using glucose as carbon source as the second phase, can achieve higher microalgal biomass and lipid production.
| Identifer | oai:union.ndltd.org:TW/099NCTU5538011 |
| Date | January 2011 |
| Creators | 林佳蓉 |
| Contributors | , 林志生, Chih-Sheng Lin |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 88 |
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