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铁对几种不同代谢类型微藻的生长和油脂积累的影响
其他题名Effect of iron on growth and lipid accumulation in several microalgae with different metabolic type
刘志媛
学位类型博士
2008-06-12
学位授予单位中国科学院海洋研究所
学位授予地点海洋研究所
关键词 生长 微藻 乙酰辅酶a羧化酶mrna 荧光分光光度法
摘要由于化石能源储量的日益减少及其燃烧带来的环境污染问题,生物柴油的开发和应用受到广泛关注。微藻因其生长迅速,油脂含量高,被认为是制备生物柴油的理想原料,另外,同陆生油料植物相比,微藻,尤其海洋微藻培养还具有不与农业争耕地和淡水、不影响食物安全保障和破坏生境的优势。然而,由于生产成本较高,微藻生物柴油至今尚未实现商业化生产。大量研究表明,微藻油脂含量和干物质产量受环境条件调控。为优化培养条件,提高微藻的油脂产量,并探索与脂积累相关的某些代谢调控因子,本文研究了铁对三种微藻油脂积累和生长的影响。 首先建立了尼罗红染色、荧光分光光度法测定微藻油脂积累的简单、快速的方法,优化了染色后的小球藻C3和C7(Chlorella vulgaris)、球等鞭金藻(Isochrysis galbana)、三角褐枝藻(Phaeodactylum tricornutum)和莱茵衣藻(Chlamydomonas reinhardtii)脂积累的测量条件。 海洋微藻小球藻C7属于绿藻门,以积累淀粉为主。在指数生长后期向培养基中补加Fe3+,可延长小球藻指数生长期,提高细胞终密度。处于指数生长后期的小球藻经离心收集、重新接种于新的高铁培养基中后,总脂含量能提高到干物质重的56.6%,是低铁培养基中小球藻的3至7倍。 球等鞭金藻属于金藻门,油脂是其贮藏物质的主要形式。在指数生长后期向培养基中补加Fe3+ 后,指数生长期延长,细胞终密度提高。将指数生长后期的球等鞭金藻重新接种于新的培养基中后,在高铁培基中的藻的总脂含量和细胞生长均高于在低铁培养基中的。 最后,研究了铁对淡水藻莱茵衣藻脂积累和生长的影响。指数生长后期的衣藻接种于无铁TAP培养基中后,利用荧光分光光度法测得的中性脂的积累量增加,生长速度下降;而重新接种于高铁培养基中后,脂积累量下降,生长加速。乙酰辅酶A羧化酶(ACCase)催化脂合成的第一步反应,是调节脂合成速度的关键酶。本实验研究结果表明,生长在不同铁浓度条件下的衣藻ACCase基因的表达水平与细胞的分裂、生长相关。
其他摘要Due to the shortages of fossil fuels and the production of greenhouse gas carbon dioxide on their combustion, biodiesel is receiving considerable attention. Microalgae are one of the most promising feedstock owing to their higher oil yields and fast growth. Moreover, microalgae especially marine microalgae, can grow in places away from farmlands and free from fresh water, thus minimizing the damages caused to the eco- and food-chain systems. However, the production of algae for biodiesel has not yet been undertaken on a commercial scale, and one of the key factors is the production of organisms. Lipids content and the dry matter yield of microalgae could be modified by environmental conditions. To optimize the cultural conditions for increasing lipids productivity in some microalgae, and to explore some metabolic controlled factors relevant to lipids accumulation, the effect of iron on growth and lipids accumulation in three microalgae species was investigated. Firstly, a simple and rapid method determining the lipid accumulation in microalgae with spectrofluorimetry was developed. Measurement conditions for lipids accumulation in Nile Red-stained algae Chlorella vulgaris C3 and C7, Isochrysis galbana , Phaeodactylum tricornutum and Chlamydomonas reinhardtii were optimized. Marine strain C. vulgaris C7 is a kind of green algae which use starch as their primary storage component. Final cell densities of C. vulgaris C7 increased and the exponential growth phase was prolonged after Fe3+ was added into media in the late growth phase. When cells in the late-exponential growth phase were collected by centrifugation and re-inoculated into new high-Fe3+ media, total lipid content was stimulated up to 56.6% biomass by dry weight and was 3–7-fold that in other media supplemented with lower iron concentration. I. galbana is golden-brown alga and lipids are considered to be the major storage products. The exponential growth phase was prolonged and the final cell density increased when I. galbana culture supplemented with Fe3+ in the late growth phase. When cells in the late-exponential growth phase were collected by centrifugation and re-inoculated into new media, both lipids content and cell densities in media with high Fe3+ concentration were higher than that with lower Fe3+ concentration. Lastly, effect of iron on growth and lipids accumulation in fresh water green microalage C. reinhardtii was studied. When cells in the late-exponential growth phase were collected by centrifugation and re-inoculated into iron depleted TAP media, neutral lipid accumulation determined with spectrofluorimetry increased and growth decreased. Inversely, neutral lipid accumulation decreased and growth increased when C. reinhardtii cells were re-inoculated into high- Fe3+ media. Acetyl CoA Carboxylase catalyses the formation of malonyl CoA. The reaction is a potential regulatory step in lipid biosynthesis. However, in C. reinhardtii cells exposed to different iron levels, positive correlation was not observed between ACCase mRNA levels and the neutral lipid. ACCase mRNA levels seemed related with cells division and growth in our study.
页数101
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/1375
专题海洋环流与波动重点实验室
推荐引用方式
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刘志媛. 铁对几种不同代谢类型微藻的生长和油脂积累的影响[D]. 海洋研究所. 中国科学院海洋研究所,2008.
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