小球藻（Chlorella vulgaris）在不同浓度Fe3+培养下的蛋白质组学初步研究

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题名	小球藻（Chlorella vulgaris）在不同浓度Fe3+培养下的蛋白质组学初步研究
作者	刘彩霞1
学位类别	硕士
答辩日期	2016-05
授予单位	中国科学院大学
授予地点	北京
导师	王广策
关键词	小球藻（Chlorella vulgaris），Fe3+，中性脂，自养，兼养，乙酸盐，蛋白质组
学位专业	海洋生物学
中文摘要	小球藻光合效率高，生长速率快，具有与高等植物相似的光合机制与代谢路径，长久以来小球藻被作为一种研究高等植物光合作用的参考生物。光能自养是指微藻利用光能，以CO₂作为碳源，通过光合作用将光能转化成化学能，并将无机碳同化为碳水化合物的过程，这种培养方式成本低。兼养是指细胞以光合作用作为主要能量来源，有机碳源和CO₂同时作为碳源进行物质同化的过程。兼养培养可以弥补特定条件下自养生长速率较慢的缺点，快速提高微藻的生物量，缩短培养时间。一定浓度范围内的Fe³⁺对小球藻的生长具有促进作用，有研究表明高浓度Fe³⁺对小球藻的油脂积累也有促进作用。本文探讨了淡水小球藻（Chlorella vulgaris）在不同浓度Fe³⁺（缺铁0、中浓度铁1.2×10^‑6和高浓度铁1.2×10^-5 mol·L^-1）培养条件下的油脂积累，并试图通过蛋白质组学的手段来探讨Fe³⁺对小球藻（C. vulgaris）油脂积累的作用机制。通过分别测定自养和兼养小球藻在不同Fe³⁺浓度条件下的生长速率和中性脂含量，确定Fe³⁺对小球藻生长速率和中性脂含量的影响；生长后期离心收集藻液，提取总可溶性蛋白，进行蛋白质组的测定分析。结果表明，自养条件下，小球藻在缺铁时中性脂含量高，但生长速率慢，生物量少。蛋白质组分析发现，自养时小球藻在缺铁和高浓度铁条件下， PS I和PS II的蛋白和糖代谢过程中相关酶表达量较低，一些与抗逆相关的蛋白，如分子伴侣、热激蛋白、细胞色素c氧化物酶和组蛋白、骨架蛋白等都在缺铁时含量升高，而且缺铁时降低更为明显。以乙酸为碳源兼养培养时，小球藻生长速率明显快于自养时生长速率，缺铁时中性脂含量也明显高于自养时缺铁培养的含量。这可能是由于兼养时，藻体可以直接吸收乙酸盐，形成乙酰CoA；缺铁时蛋白合成受到限制，多余的碳进入脂肪酸合成路径，合成大量中性脂；高浓度铁条件下乙酰CoA则进入三羧酸循环路径，呼吸加快，为藻体生长提供更多能量。兼养时藻细胞直接利用乙酸盐比自养时利用CO₂生成有机物速率快，因此三羧酸循环相关蛋白在缺铁时含量增多，促进生长。
英文摘要	Due to its photosynthesis efficiency, high growth rate, and photosynthetic machinery and metabolic pathways similar to higher plants, Chlorella has long been used as a model organism to understand photosynthesis in higher plants. Photoautotrophic is referred to the cells that harvest light energy convert into chemical energy by photosynthetic reaction , and assimilate CO₂ as a carbon source , and inorganic carbon can be assimilated for carbohydrate synthesis. The cost of photoautotrophic culture is low. Mixtrophic is referred to cells that rely on photosynthesis as the main energy source, meanwhile, both organic components and CO₂ are required. Mixtrophic culture could compensate for the low bimass of autotrophic culture, and receive a rapid growth of biomass with shortening culture time. The growth rate of Chlorella was promoted by iron, previous studies showed that oil accumulation of Chlorella was also improved by high concentration iron. This research investigated the lipid accumulation process of freshwater Chlorella vulgaris under different iron concentrations conditions (low iron concentration 0, middle iron concentration 1.2×10^‑6, hign iron concentration 1.2×10^-5 mol·L^-1) and proteomics was used to explain the response mechanism of C. vulgaris to iron. In this research, the growth rate and neutral lipid content of autotrophic C. vulgaris were determined under different iron concentrations. Cells in late growth phase were collected by centrifugation and protein was extracted for proteomic analysis. When cultured photoautotrophicly, the neutral lipid content of C. vulgaris was highest under iron deficiency condition and the growth rate was slowest and biomass was lowest. Proteomics analysis revealed that C. vulgaris which was cultured under low and high iron concentrations conditions were in stress, the function of PSI and PS II impaired, the rate of electron transport and carbon fixation declined, and carbohydrate metabolism related proteins decreased. Proteins which were related to resistance increased under iron-deficiency and iron-replete conditions, but stress under iron-deficiency condition was more serious. Results showed that the growth rate of mixtrophic C. vulgaris was faster than that of autotrophic , and the content of neutral lipid was higher in mixtrophic culture than that in autotrophic condition. This maybe due to the algae could use acetate directly to convert into acteyl CoA, when under iron-deficiency condition acteyl CoA influxed into fatty acid synthesis pathway to synthesize large amounts of neutral lipids. When under iron-replete condition acteyl CoA influxed into tricarboxylic acid cycle pathway to accelerate respiration rate. Acetate was directed used by algae cells which was faster than carbon fixation cultured photoautotrophic. The content of proteins related tricarboxylic acid cycle pathway were increased under iron-deficiency condition and growth rate was promoted. Key words: Chlorella vulgaris, Fe³⁺, neutral lipid, autotrophic, mixtrophic, acetate, proteomics
语种	中文
学科主题	海洋生物学
内容类型	学位论文
源URL	[http://ir.qdio.ac.cn/handle/337002/112568]
专题	海洋研究所_实验海洋生物学重点实验室
作者单位	1.中国科学院海洋研究所 2.中国科学院大学
推荐引用方式 GB/T 7714	刘彩霞. 小球藻（Chlorella vulgaris）在不同浓度Fe3+培养下的蛋白质组学初步研究[D]. 北京. 中国科学院大学. 2016.