生态因素对海洋微藻蛋白质含量的影响

考察了光照时间,培养温度,二氧化碳通入量等生态因素对处于不同生长时期的小球藻,等鞭金藻,新月菱形藻中的蛋白质含量的影响。结果表明,不同种类的微藻,生态因素对其胞内蛋白质含量的影响不同,小球藻在光照17h,培养温度19℃,每日间歇通入25mLCO2/L培养液的条件下,培养至对数对数生长期,蛋白质含量达到70%;等鞭金藻在光照17h,培养温度19℃以上,不通入CO2的条件下培养至静止期,蛋白质含量接近70%;新月菱形藻光照17h,培养温度25℃,不通入CO2的条件下培养至对数对数生长期,蛋白质含量超过70%。     

三种环境激素对四种海洋微藻的急性毒性效应研究

近年来,海洋环境激素污染日益严重,为了考察环境激素对海洋微藻的生物毒性效应,进而评估其对海洋生态系统的影响,该实验研究了三氯卡班、邻苯二甲酸二丁酯、三丁基氯化锡三种环境激素对海洋小球藻(Chlorella sp.)、眼点拟微绿球藻(Nannochloropsis ocutala)、球形棕囊藻(Phaeocystis globosa)和东海原甲藻(Prorocentrum donghaiense )4种海洋微藻的急性毒性效应。结果表明,三种环境激素均可显著抑制该4种微藻的生长。三氯卡班对4种微藻的96 h-EC₅₀分别为108.19 μg·L^-1、63.21 μg·L^-1、60.73 μg·L^-1和57.58 μg·L^-1;邻苯二甲酸二丁酯对4种微藻的96 h-EC₅₀分别为1.42 mg·L^-1、1.02 mg·L^-1、1.47 mg·L^-1 和1.21 mg·L^-1;三丁基氯化锡对4种微藻的96 h-EC₅₀分别为3.5 μg·L^-1、4.36 μg·L^-1、0.6 μg·L^-1和0.6 μg·L^-1。三种环境激素对四种海洋微藻的毒性强弱顺序为三丁基氯化锡>三氯卡班>邻苯二甲酸二丁酯。     

低浓度毒物对海洋微藻生长刺激效应的初步研究

1　引　　言毒物刺激效应又称毒物兴奋效应 ,是指毒物在较低的浓度下 ,对生物非但无害而且表现出刺激生长的现象 .Ｓｔｅｂ ｂｉｎｇ[10 ] 称这种现象为毒物刺激效应 (ｈｏｒｍｅｓｉｓ) .目前已有许多报道表明 ,低浓度的污染物或毒物普遍对海洋微藻的生长具有刺激效应 ,并被推测是导致赤潮产生的重要环节[5,7,13 ] .另外 ,已有文章报道 ,海洋微藻的生长繁殖与藻液中的微生物密切相关 .因此 ,推测低浓度毒物对海洋微藻的生长刺激效应与海洋微藻生活环境中的微生物也有着一定的关系 .但是 ,关于这方面的研究还未见报道 .在少有的有关毒物刺激…     

海洋微藻脂肪酸去饱和酶

海洋微藻中富含多不饱和脂肪酸(polyunsaturated fatty acid,PUFA),在部分微藻中ω3 PUFA的量可达其总脂肪酸的30%～50%。而且微藻油具有鱼油所不可比拟的健康优势,也是唯一得到美国食品与药物管理局(FDA)认可的儿童DHA(二十二碳六烯酸)补充剂来源。由于用培养微藻来提取、纯化PUFA受到现有生产工艺的限制,使微藻油在国际食品(尤其是高质量食品)及保健品市场上供不应求。微藻脂肪酸去饱和酶(fatty aciddesaturase,FAD)是微藻PUFA合成的关键酶类,所以对微藻FAD的深入研究无疑将促进PUFA资源的合理开发和利用。     

几种海洋微藻的氨基酸含量

分析测定分属硅藻,绿藻和蓝藻的７种海洋饵料微藻氮和氨基酸含量。氮含量范围为４．０４％～９．８６％,总氨基酸中共测出１７种氨基酸,含量范围为１．２３％～９．７４％。名藻的总氨基酸含量顺序与氮含量相同     

海洋微藻基因工程的选择标记

６种海洋微藻新月菱形藻（Ｎｉｔｚｓｃｈｉａ ｃｌｏｓｔｅｒｉｕｍ Ｅｈｒ．）、牟勒氏角刺藻（Ｃｈａｅｔｏｃｄｒｏｓ ｍｕｅｌｌｅｒｉ Ｌｅｍｍ．）、三角褐指灌（Ｐｈａｅｏｄａｃｔｙｌｕｍ ｔｒｉｃｏｒｎｕｔｕｍ Ｂｏｈｌ．）绿光等鞭金藻８７０１（Ｉｓｏｃｈｒｙｓｉｓ ｇａｌｂａｎａ Ｐａｒｋｅ ８７０１）、亚心形扁藻（Ｐｌａｔｙｍｏｎａｓ ｓｕｂｃｏｒｄｉ－ｆｏｒｍｉｓ（Ｗｉｌｌｅ）Ｈａｚｅｎ）和     

利用海洋微藻生产富含DHA的单细胞油脂

ＤＨＡ是神经组织的基本组分,人体合成ＤＨＡ的能力有限,从饮食中摄取足够的ＤＨＡ十分重要。特别是婴幼儿缺乏ＤＨＡ会影响智力、视力和生理发育。鱼油是目前ＤＨＡ的最普遍来源,但是鱼油的产量和质量难以满足人们的需要。利用生物技术生产ＤＨＡ是发展方向,研究得最多的是用海洋真菌和藻类生产ＤＨＡ,其中用海洋藻类Ｃｒｙｐｔｈｅｃｏｄｉｎｉｕｍ ｃｏｈｎｉｉ生产富含ＤＨＡ的单细胞油脂已达工业化规模,而且产品的稳定性,纯度,安全性和生物利用率都优于鱼油,目前已应用于婴儿奶粉和作为辅助食品。     

低浓度蒽对两种海洋微藻生长的兴奋效应

以两种海洋微藻金藻 870 1(Isochrysisgalbana 870 1)和骨条藻 (Skeletonemacostatum )为材料 ,研究了低浓度蒽 (1 5～ 6 μg·L-1)对两种海洋微藻生长的影响 .结果表明 ,在一定浓度蒽作用下 ,两种微藻的生长均呈现出较明显的“兴奋效应” ,细胞密度有所增加 ,但达到最佳刺激作用的浓度与时间有所不同 .在刺激浓度作用下 ,两种微藻体内的蛋白质、叶绿素a(chla .)、类胡萝卜素 (car.)含量都有所增加 ,其变化趋势与细胞密度的变化类似 .在整个实验过程中 ,微藻体内清除活性氧的关键性酶超氧化物歧化酶 (SOD)始终处于较高水平 ,其变化趋势类似于细胞密度的变化     

基因芯片在海洋微藻研究中的应用前景

基因芯片通常指DNA芯片,其基本原理是将大量的寡核苷酸分子固定于支持物上,然后与标记的样品进行杂交,通过检测杂交信号从而获取结果。多年来,我国在医药疾病研究、微生物检测等领域已成功研制出多种基因芯片,取得了骄人的成绩,但在对海洋微藻研究的应用上成果较少。现着力从实际应用的角度阐述基因芯片及其在海洋微藻研究中的应用。     

海洋微藻对重金属镉胁迫的抗氧化应激适应性

近海海域重金属镉污染已成为全球性的环境灾难。镉对有机体的氧化应激胁迫是引发有机体毒害效应的关键原因。海洋微藻是海域生态系统中初级生产者,研究其抵抗镉氧化应激毒害的过程和机理对海洋生态学具有重要科学意义。海洋微藻在长期进化发展过程中,形成了耐受重金属镉毒害的生长适应性反应,抵抗镉氧化应激胁迫是海洋微藻减轻或消除镉毒害的关键所在。文章概述当前近海重金属镉的污染现状,归纳重金属镉对海洋微藻的氧化应激毒害效应,提出海洋微藻对镉胁迫的抗氧化应激适应性,简介几种典型的抗氧化应激酶类与非酶类物质,最后指出该领域的关键问题并进行展望。     

Behavior of dimethyl phthalate (DMP) in simulated landfill bioreactors with different operation modes

The behavior of dimethyl phthalate (DMP) from municipal solid waste (MSW) in the leachate and refuse of two simulated landfill bioreactors was compared. In one reactor, the leachate was circulated between a landfill and a methanogenic reactor, while the other reactor was operated using direct recirculation of the leachate. The results revealed that the original concentration of DMP in the refuse was approximately 3.3 μg g⁻¹, and the concentration decreased greatly during decomposition of the waste in both reactors. The major loss of DMP from the landfill occurred in an active methanogenic environment in the later period, while the environment was acidic due to a high concentration of chemical oxygen demand (COD), volatile fatty acids (VFA), and contained a large volume of biologically degradable material (BDM) during the early stage. In addition, a high correlation was found between the residual DMP concentrations and the BDM of the refuse in both systems. Circulating the leachate between the landfill and a methanogenic reactor resulted in an increase in the biodegradability of MSW and the degree of waste stabilization. Furthermore, the removal of DMP was enhanced 14% in the landfill that was operated in conjunction with the methanogenic reactor when compared to the landfill in which there was direct leachate recirculation.     

Screening of marine microalgae for bioremediation of cadmium-polluted seawater

Twenty four strains out of 191 marine microalgal strains exhibited cadmium (Cd) resistance. They were tested for their Cd removal ability in growth media containing 50 μM Cd. Six strains out of 19 green algae and one out of five cyanobacteria removed more than 10% of total Cd from the medium. The marine green alga Chlorella sp. NKG16014 showed the highest removal of Cd 48.7% of total. Cd removal by NKG16014 was further quantitatively evaluated by measuring the amount of cell adsorption and intracellular accumulation. After 12 days incubation, 67% of the removed Cd was accumulated intracellularly and 25% of the Cd removed was adsorbed on the algal cell surface. The maximum Cd adsorption (q_max) was estimated to be 37.0 mg Cd (g dry cells)⁻¹ using the Langmuir sorption model. The Cd removal by freeze-dried NKG16014 cells was also determined. Cd was more quickly adsorbed by dried cells than that by living cells, with a q_max of 91.0 mg Cd (g dry cells)⁻¹.     

Increased lipid production of the marine oleaginous microalgae Isochrysis zhangjiangensis (Chrysophyta) by nitrogen supplement

Effects of nitrate feeding on the cell growth and lipid accumulation of marine microalgae Isochrysis zhangjiangensis were investigated. When nitrate was supplied at interval of 24 h, instead of 72 h, a high lipid content of 40.9% and a biomass density of 3.1 g L⁻¹ were obtained. To confirm whether I. zhangjiangensis accumulates lipid during nitrogen-repletion, a two-stage cultivation method was applied. This algal strain had a high lipid content during sustained nitrate addition and showed a high carbohydrate content under nitrate-depletion conditions. These results revealed that this algal strain can accumulate lipids under nitrogen-repletion conditions and accumulate carbohydrate under nitrogen-depletion conditions. When cultured in an extremely high nitrate concentration, 9 g L⁻¹ at 24 h intervals, the growth of algal cells was suppressed, but the highest lipid content of 53% was attained. This special characteristic of lipid accumulation makes I. zhangjiangensis an ideal candidate for producing biodiesel using N-rich wastewater.     

Vitamin content of four marine microalgae. Potential use as source of vitamins in nutrition

Summary Certain marine microalgae contain water-and lipid-soluble vitamins and can be used as food supplements or food ingredients. A number of vitamins are present in higher concentrations in the microalgae than in conventional foods traditionally considered rich in them. Ingestion of relatively small quantities of microalgae can cover the requirements for some vitamins in animal nutrition, including human nutrition, while supplementing others. Marine microalgae can thus be considered to represent a non-conventional source of vitamins or a vitamin supplement for animal or human nutrition.     

Biodegradation of dimethyl phthalate by an entomopathogenic nematode symbiont Xenorhabdus indica strain KB-3

Dimethyl phthalate (DMP) a common environmental pollutant is well known for its endocrine disrupting activities. Wide spread use of the plastics and pesticides in agriculture have resulted in DMP pollution in soils. An endosymbiotic bacteria Xenorhabdus indica isolated from entomopathogenic nematode Steinernema thermophilum was investigated for biodegradation of DMP. Biodegradation experiment was conducted for 12 days in minimal salt medium supplemented with beef extract. Quantification of residual DMP by High performance liquid chromatography (HPLC) revealed that maximum degradation (98.75%) occurred at 9th day of incubation along with higher esterase activity (46.94 IU/ml) and growth of bacteria (263.75 μg/ml). The efficacy of purified esterase for degradation of DMP was also investigated. It was observed that enzyme alone transform more than 25.6% of DMP into mono-methyl phthalate (MMP) and phthalic acid (PA) within 24 h, which confirms its role in degradation of DMP. Activity of carboxyl esterase enzyme was also positively correlated (r = 0.88) with biodegradation of DMP. Xenorhabdus completely mineralized the DMP as the two intermediates mono-methyl phthalate (MMP) and phthalic acid were not detected after the incubation period of 12 days. The results suggest that the X. indica was highly efficient in degrading DMP and can be employed for bioremediation of contaminated sites.     

The distribution of benthic marine algae

Hitherto only gametangial and carposporangial phases of Thuretellopsis peggiana Kylin have been reported. A study of this rare member of the Dumontiaceae (Cryptonemiales) in culture has disclosed the existence of an encrusting tetrasporangial phase, previously unknown, whilst the life history has been shown to be of the ‘Bonnemaisonia’ type.     

Inorganic-carbon transport in some marine eukaryotic microalgae

Inorganic-carbon transport was investigated in the eukaryotic marine microalgaeStichococcus minor, Nannochloropsis oculata and aMonallantus sp. Photosynthetic O₂ evolution at constant inorganic-carbon concentration but varying pH showed thatS. minor had a greater capacity for CO₂ rather than HCO ₃ ^– utilization but forN. oculata andMonallantus HCO ₃ ^– was the preferred source of inorganic carbon. All three microalgae had a low affinity for CO₂ as shown by the measurement of inorganic-carbon-dependent photosynthetic O₂ evolution at pH 5.0. At pH 8.3, where HCO ₃ ^– is the predominant form of inorganic carbon, the concentration of inorganic carbon required for half-maximal rate of photosynthetic O₂ evolution [K _0.5 (CO₂)] was 53 M forMonallantus sp. and 125 M forN. oculata, values compatible with HCO ₃ ^– transport. Neither extra- nor intracellular carbonic anhydrase was detected in these three microalgal species. It is concluded that these microalgae lack a specific transport system for CO₂ but that HCO ₃ ^– transport occurs inN. oculata andMonallantus, and in the absence of intracellular carbonic anhydrase the conversion of HCO ₃ ^– to CO₂ may be facilitated by the internal pH of the cell.     

Alkali-labile precursors of dimethyl sulfide in marine benthic cyanobacteria

By the method of cold alkali hydrolysis, 29 marine benthic cyanobacteria were screened for production of alkali-labile precursors of dimethyl sulfide (DMS) including dimethylsulfoniopropionate (DMSP), a compound of significant importance in marine environments. Concentrations of DMS precursors ranged from undetectable to 0.8 mmol (g Chl a)^–1. The data correspond to some previous investigations concerning DMSP content of marine cyanobacteria and suggest that marine benthic cyanobacteria are only minor producers of DMSP. Received: 3 July 1997 / Accepted: 21 October 1997