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题名: 铒料微藻的特性及其与CO_2浓度变化的关系研究
作者: 胡晗华
答辩日期: 2001
导师: 高坤山
专业: 水生生物学
授予单位: 中国科学院水生生物研究所
授予地点: 中国科学院水生生物研究所
学位: 博士
关键词: 海生椭球藻 ; 牟氏角毛藻 ; 谷皮菱形藻 ; 饵料微藻 ; 生化组成 ; 多不饱和脂肪酸 ; 光合作用 ; C0_2升高
摘要: 海生椭球藻是从天然水体中筛选到的一个新种,已被用作珍贵水产品育苗的开口饵料;牟氏角毛藻(Chaetoceros muelleri)和谷皮菱形藻(Nitzschiapalea(Kiitz.)W.Smith)是水产养殖中常用的饵料藻种。本文在综述了饵料微藻、微藻脂肪酸研究概况、黄藻及相关门类的分类色素及进化、真核微藻的光合固碳的基础上,在以下三个方面进行了研究:①海生椭球藻的基本生物学特点,包括其分类、进化、起源和作为优良饵料直至EPA生产资源的可行性;②高CO_2浓度下不同环境因子(碳源、氮磷浓度、盐度和温度等)对海生椭球藻生长、生化组成和光合作用的影响;③淡水产和海产硅藻对CO_2浓度升高的响应。主要结果如下:从中国东海海域采集并分离得到的一种黄绿色单细胞超微型藻(品系PP983)多为椭球形,少为球形,含一个细胞核,形态观察结合色素分析表明它是黄藻门(Xanthophyta)、柄球藻目(Mischococcales)、椭球藻属(Ellipsoidion)中的一个新种,被定名为海生椭球藻(Ellipsoidion maratilis Shi et Hu,sp. nov.)。该藻不含叶绿素c,含多甲藻素并以pCP(Peridinin-Chlorophylla-Protein Complexes)的形式存在于藻细胞的叶绿体中,起捕获光能的作用。海生椭球藻对温度具有很好的适应能力且是广盐性种类,在天然海水中可达到较佳生长。在最适条件下(25 ℃和100/μmolphotonm~(-2)s~(-1)),其比生长速率为1.2 d~(-1),对数生长期的蛋白质含量高达40%(W/W),含全部必需氨基酸(占干重的13%)及丰富的多不饱和脂肪酸(占总脂肪酸的32%)。该藻所含EPA在其脂肪酸中占22.9%,是干重的4.6%。海生椭球藻对低盐良好的耐受性表明该藻可能起源于淡水。多甲藻素在该种的存在显示了黄藻在进化上与甲藻有较近的亲源关系。不同碳源及高CO_2浓度条件下海生椭球藻的生长、光合作用、营养组成有差异。碳限制时,添加醋酸钠(2 mmol L~(-1))和提高C0_2浓度均促进海生椭球藻的生长,使稳定期生物量分别增加9%和39%。高浓度CO_2(2800μL L~(-1) CO_2)、醋酸钠、高氮和低盐明显地增加了藻细胞色素含量;高氮和高磷促进了其蛋白质合成,高CO_2、低氮和低磷则有利于细胞脂肪和碳水化合物的积累。盐度变化对藻细胞中脂肪、蛋白质和碳水化合物的含量影响不大;不同温度下藻细胞碳水化合物含量基本保挣恒定,但高温和低温均导致细胞脂肪和蛋白质不同程度增加。高氮、高磷和低温,提高了藻细胞脂肪酸中PUFAs的比例,但使细胞的总脂肪酸含量减少了;低氮、低磷和高温,促进了藻细胞总脂肪酸合成,但降低了脂肪酸中PUFAs的比例。低盐既利于细胞脂肪酸合成又可导致脂肪酸中PUFAs的比例增加。与对照相比,醋酸钠的添加降低了细胞总脂肪酸和PUFAs的比例。高CO_2浓度(2800μL L~(-1) CO_2)显著地提高了藻细胞脂肪酸的含量和PUFAs的相对比例,使其EPA含量比对照(350μL L~(-1) CO_2)增加了27%。显然,提高CO_2浓度可以有效地调控微藻多不饱和脂肪酸的合成。高CO_2浓度条件下,该藻光合作用对无机碳的亲和力与培养基中NO_3的浓度相关,起初随NO_3~-浓度升高而增加,至600μmol L~(-1)时,达到最大值,之后随培养基中NO_3~-浓度的进一步升高而快速下降。谷皮菱形藻(淡水)和牟氏角毛藻(海水),在C0_2浓度倍增(700μL L~(-1) CO_2)条件下,前者的生长从对数期开始受到促进,而后者的促进出现在对数末期;CO_2浓度倍增使稳定期的最大生物量(干重),谷皮菱形藻增加4-20%,牟氏角毛藻增加11-31%。CO_2倍增不影响两种硅藻细胞中各种色素的相对比例。高CO_2培养后谷皮菱形藻的暗呼吸速率有所降低,饱和光强高于对照组,而牟氏角毛藻则相反。随着培养液中DIC浓度的增加,以单位细胞表示的光合作用光饱和速率及光限制部分初始斜率升高。两种藻光合作用时均能利用HCO_3~-,对HCO_3~-和CO_2的亲和力,在CO_2浓度倍增条件下,明显降低。
英文摘要: Ellipsoidion maratilis Shi et Hu is a new species isolated from the surface seawater in the East Sea of China, and has been used in aquaculture. Chaetoceros muelleri and Nitzschia palea are foods for some of larval stages of the most valuable aquatic organisms. Research progresses on microalgae as foods in aquaculture, fatty acids of microalgae, and inorganic carbon utilization ofeukaryotic microalgae have been reviewed. On that basis, the investigations were carried out on the biological characteristics, regulation of its biochemical composition, the photosynthetic responses to environmental factors of Ellipsoidion maratilis and the comparative responses of Chaetoceros muelleri (marine) and Nitzschia palea (freshwater) to elevated CO_2. The marine yellowish-green alga (strain PP983), often ellipsoidal, occasionally spherical, 3-4μm long, 2.5-3μm wide, contains one nucleolus. Morphological features and pigment composition analysis showed that this alga was a new species of the Xanthophyta (Mischococcales) and was named as Ellipsoidion maratilis Shi et Hu. No chlc was detected in this alga, but peridinin (representative of Dinophytes) was found in a water-soluble pigment-protein complex, peridinin-chlorophyll a-protein complex (PCP). This complex presumably harvests light in vivo for photosynthesis. This alga is a euryhalinous species, and grows well in natural seawater without enrichment of nutrients. Under optimum condition (25 ℃, 100μmol photon m~(-2) s~(-1)), its specific growth rate was 1.2 d~(-1). The algal biomass at logarithmic-phase contained 40% (W/W) protein with all kinds of essential amino acids (13% of dry mass), and rich polyunsaturated fatty acids (PUFAs), about 32% of the total fatty acids. EPA coment was as higher as 46 mg g~(-1) dried cells, indicating that Ellipsoidion maratilis is of high potential to generate EPA. The high adaptability of Ellipsoidion maratilis to low salinifies suggested that this species might have originated from freshwater. The occurrence of peridinin in the alga shows that Xanthophyta is closely related Dinophyta in terms of evolution. Addition of sodium acetate and elevation of CO_2 concentration enhanced the growth of Ellipsoidion maratilis. Biomass (dry weight) at stationary phase increased by 39% under the high CO_2 level (2800μL L~(-1) CO_2), and by 9% under the mixotrophic condition. The pigment content increased markedly under high CO_2 concentration, mixotrophic culture, high NaNO_3 level and low salinity conditions, respectively. High concentrations of NaNO_3 and KH_2PO_4 resulted in high protein content; high CO_2, low NaNO_3 and KH_2PO_4 gave rise to high contents of carbohydrate and lipid. Protein, carbohydrate and lipid were approximately at the same level under varied salinities. Variation in temperature did not affect the content of carbohydrate, but high temperature or low temperature raised the contents of protein and lipid. High NO_3~-, PO_4~(3-) and low temperature brought about better synthesis of PUFAs, though it lowed the content of total fatty acids (TFA). Low salinity not only improved the TFA content but also enhanced the accumulation of PUFAs. The mixotrophic culture brought about lower TFA and PUFAs. Elevation of CO_2 concentration (2800μL L~(-1) CO_2) increased the amount of TFA and PUFAs, with EPA being increased by 27%. It was found that elevation of CO_2 is an effective way for the production of PUFAs. At 2800 μL L~(-1) CO_2, the affinity of algal cells to DIC increased with increased NO_3~- concentrations and reached its maximum at 600 μmol L~(-1) NO_3~-, and then decreased with further elevated NO_3~- concentrations. Elevated CO_2 to 700μL L~(-l) enhanced the growth of Nitzschia palea by 4-20% at the beginning of exponential phase, and that of Chaetoceros muelleri by 11-31% in the late exponential phase. Pigment composition did not alter with the increase of CO_2 concentration. High CO_2-grown Nitzschia palea cells showed lower levels of dark respiration and higher I_k values, while the Chaetoceros muelleri cells showed the contrary results. Elevation CO_2 concentration increased light-saturated photosynthetic and photosynthetic efficiency per cell. Both Nitzschia palea and Chaetocero muelleri were capable of using HCO_3~-, under the doubled CO_2, the affinity of they to HCO_3~- and CO_2 decreased.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ihb.ac.cn/handle/342005/12576
Appears in Collections:中科院水生所知识产出(2009年前)_学位论文

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铒料微藻的特性及其与CO_2浓度变化的关系研究.胡晗华[d].中国科学院水生生物研究所,2001.20-25
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