钝顶螺旋藻突变株FBL细胞超微结构

利用透射电镜技术观察钝顶螺旋藻出发株和突变株FBL的细胞超微结构。观察结果表明L出发株和突变株均为多细胞丝状体,细胞间横隔膜清晰,细胞壁均由四层结构组成,细胞质膜内陷形成类囊体,类囊体由双层膜堆积而成,膜上附着藻胆体,类囊体与细胞壁呈垂直方向排列,细胞质内包含有充气液泡等细胞器。与出发株相比,突变株细胞壁表面较光滑,四层结构电子密度较深;类囊体膜增多、变发达;羧化体数量增多;横隔膜收缢明显。     

Cadmium biosorption on Spirulina platensis biomass

Dry biomass of Spirulina platensis re-hydrated for 48 h was employed as a biosorbent in tests of cadmium(II) removal from water. Various concentrations of biomass (from 1 to 4 g l⁻¹) and metal (from 100 to 800 mg l⁻¹) were tested. Low biomass levels (X_o  2 g l⁻¹) ensured metal removal up to 98% only at Cd₀= 100 and 200 mg l⁻¹, while X_o  2.0 g l⁻¹ were needed at Cd₀ = 400 mg l⁻¹ to achieve satisfactory results. Whereas X_o = 4.0 g l⁻¹ was effective to remove up to Cd₀ = 500 mg l⁻¹, a further increase in metal concentration (Cd₀ = 600 and 800 mg l⁻¹) led to progressive worsening of the system performance. At a given biomass levels, the kinetics of the process was better at low Cd²⁺ concentrations, while, raising the adsorbent level from 1.0 to 2.0 g l⁻¹ and then to 4.0 g l⁻¹, the rate constant of biosorption increased by about one order of magnitude in both cases and the adsorption capacity of the system progressively decreased from 357 to 149 mg g⁻¹.     

富硒螺旋藻中硒别藻蓝蛋白的纯化及其特性

从富硒螺旋藻(Se richSpirulina platensis,Se-SP)中分离纯化高纯度的含硒别藻蓝蛋白(Se-containingallophycocyanin,Se-APC)并观察其生化特性。羟基磷灰石和DEAE-52柱层析方法结合制备电泳技术纯化Se-APC;光谱扫描、Native-PAGE、SDS-PAGE和IEF方法鉴定Se-APC生化特性;2,3-DAN荧光光度法检测蛋白质中Se含量。结果发现3种高纯度Se-APC的光谱特征分别与APCI、APCII、APCIII吻合;电泳鉴定它们可能都是(αβ)3,α、β亚基分别为18.3和15.7 kDa,其pI值分别为:4.76、4.85和5.02;3种Se-APC中Se含量分别为316、273和408μg/g,Se-APC经0.5mol/L NaSCN解聚和β-巯基乙醇变性处理后,蛋白质中Se含量依次减低并趋于稳定。结果提示Se-SP中APC可结合Se,APC中Se含量与其分子聚态有关,亚基中含Se量稳定,可能是以共价键方式结合,Se-APC生物活性及硒在蛋白质中的结合位点值得深入研究。     

A new model of phycobilisome in Spirulina platensis

Phycobilisomes (PBS) were isolated from blue-green alga Spirulina platensis. Scanning tunneling microscope was used to investigate the three-dimensional structure of PBS deposited on freshly cleaved highly oriented py-rolytic graphite (HOPG) in ambient condition at room temperature. The results showed that the rods of PBS radiated from the core to different directions in the space other than arrayed in one plane, which was different from the typical hemi-discoidal model structure. The diameter of PBS was up to 70 nm, and the rod was approximately 50 nm in length. Similar results were observed in Langmuir-Blodgett (LB) film of PBS. The dissociated PBS could reaggregate into rod-like structures and easily form two-dimensional membrane while being absorbed on HOPG, however, no intact PBS was observed. The filling-space model structure of PBS in Spirulina platensis with STM from three-dimensional real space at nanometer scale was found, which showed that this new structural model of PBS surely exists in blue     

钝顶螺旋藻(Spirulina platensis)光系统Ⅰ的分离表征及稳定性

采用蔗糖密度梯度离心法对钝顶螺旋藻光合膜蛋白(PSI)进行分离纯化,并对其光谱学性质、热稳定性及光合放氧活性进行分析表征。结果发现,采用蔗糖密度精度离心法,可以成功分离出4条色素蛋白质复合体条带,其中最下层条带为完整的PSI三聚体,其每毫克叶绿素a光合放氧活性达到420μmol/h。当温度达到50℃左右时,分离得到的PSI在溶液开始变性失活。     

螺旋藻多糖抗单纯疱疹病毒作用的实验研究

在体外进行了钝顶螺旋藻多糖(polysaccharides fromSpirulina platensis,PSP)抗单纯疱疹病毒活性的研究。以不同剂量的PSP分别作用于HSV-1及HSV-2病毒复制周期的各个环节,以病毒半数感染量(TCID50),细胞病变效应(CPE),蚀斑形成单位(PFU),MTT染色细胞保护率(MTT法)作为评价指标,判断PSP的抗病毒效果;FQ-PCR检测PSP抗病毒作用的时效关系。结果表明PSP对Vero细胞毒性极低(TC50为1750μg/mL),对HSV-1及HSV-2均无直接灭活作用,可阻滞HSV-1及HSV-2病毒吸附和抑制感染细胞内病毒的复制,但不影响病毒的释放;FQ-PCR结果显示随着PSP浓度及作用时间的增加,PSP对HSV-1病毒DNA的抑制作用明显增强,具有良好的剂量和时效关系。提示PSP抗HSV-1及HSV-2病毒作用的机制与抑制病毒吸附和感染细胞内病毒的生物合成有关。     

Production and regeneration of spheroplasts from the cyanobacterium Spirulina platensis

Abstract The development of a micro-method for the production and regeneration of spheroplasts starting from S. platensis trichomes is presented. The influence of the growth stage along with different treatments and conditions on the efficiency of spheroplast formation and regeneration are analyzed.     

Isolation and Photosynthesis of Spheroplasts in Spirulina platensis

Spirulina platensis is a nonheterocystic filamentous blue-green alga (cyanobacterium). Large quantity of highly qualified spheroplasts were obtained by improved isolation method. The spheroplast has a wrinkled and porous surface. Their diameter ranged from 3.8 btm to 4. 6 μm. The activity of photosynthetic oxygen evolution in the spheroplasts was about 40 % of the intact cell. The absorption spectra of the filaments and spheroplasts at room temperature revealed that they had the same pigments, Chla, PC, PEC and carotenoid. In spheroplasts the relative content of PC and carotenoid decreased, and that of PEC increased. It implicated that the light absorption of Spirulina platensis could be influenced by the cell wall. Some differences existed between the original cells and spheroplasts in the low temperature fluorescence emission spectra. F757 of spheroplasts excited by 436 nm was reduced obviously and that excited by 580 nm was disapeared. F728/F685 and F640/F685 enhanced, and F693/F685 was reduced. F728/F640 was lower than that of the original cells. These results indicated that removing the cell wall may inhibit the PS Ⅱ activity and influence the F695 from core antenna pigment system.     

基于蛋白质组学对螺旋藻砷胁迫响应机制的研究

通过研究螺旋藻(Spirulina sp.)在砷离子胁迫下的蛋白质组变化,从蛋白质表达水平解释螺旋藻对砷离子胁迫的响应机理。螺旋藻经过不同浓度砷离子胁迫7 d后,提取蛋白质进行凝胶电泳,并对差异蛋白进行质谱分析。结果表明螺旋藻在2.0 ppm砷酸盐中暴露10 min光合放氧速率降低27.3%,培养24 h后细胞内的金属硫蛋白、叶绿素、类胡萝卜素及藻胆蛋白相对含量均明显降低。蛋白组学共鉴定出75个差异蛋白,其中26个显著上调,49个呈现下调。这些差异蛋白表明砷离子主要通过破坏螺旋藻光合色素蛋白,干扰电子传递过程,导致能量合成受损,使得依赖光合作用产生能量进行的跨膜运动、蛋白质合成等相关过程受到影响;同时,活性氧清除与防御相关蛋白呈现上调,螺旋藻细胞内抗氧化系统被激活。     

Separation and nanoencapsulation of antitumor polypeptide from Spirulina platensis

Spirulina platensis is a multicellular edible blue‐green alga with abundant proteins (～60%). No report is available on the antitumor polypeptides from the whole proteins of S. platensis. In this study, for the first time, an antitumor polypeptide Y2 from trypsin digest of S. platensis proteins was obtained by using freeze‐thawing plus ultrasonication extraction, hydrolysis with four enzymes (trypsin, alcalase, papain, and pepsin), and gel filtration chromatography. The results showed that the degree of hydrolysis can be ordered as: trypsin (38.5%) > alcalase (31.2%) > papain (27.8%) > pepsin (7.1%). For MCF‐7 and HepG2 cells, at 250 µg/mL, the maximum inhibitory rate of Y2 was 97%, while standard drug 5‐FU was 55 and 97%, respectively. Furthermore, the nanoencapsulation of Y2 with chitosan (CS) was also investigated. After nanoencapsulation, the maximum encapsulation efficiency and polypeptides contents are 49 and 15%, respectively; and the antitumor activity is basically not lost. These data demonstrated the potential of nanopolypeptides (Y2‐CS) in food and pharmaceutical applications. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1230–1238, 2013     

钝顶螺旋藻FtsZ在大肠杆菌中的表达和定位

FtsZ是与真核微管蛋白类似的原核骨架蛋白,能在细胞分裂位点聚合组装成环状结构而调控细胞分裂过程。为了研究钝顶螺旋藻（Spirulina platensis）FtsZ蛋白的功能,构建了钝顶螺旋藻FtsZ与绿色荧光蛋白GFP融合表达的质粒,并在大肠杆菌中进行了表达和定位研究,结果发现,表达融合蛋白GFP-FtsZ的大肠杆菌细胞由短杆状变为长丝状,且菌丝体长度与融合蛋白的表达量呈正比。在荧光显微镜下观察到融合蛋白GFP-FtsZ在长丝状体细菌中呈有规律的点状分布,这说明FtsZ蛋白功能高度保守,钝顶螺旋藻FtsZ蛋白能识别大肠杆菌分裂位点并装配成环状结构调控大肠杆菌细胞分裂,FtsZ蛋白的过量表达能抑制大肠杆菌正常的细胞分裂而导致长丝状体细胞的形成。     

螺旋藻多糖抗柯萨奇B3病毒的体外实验研究

在体外进行了钝顶螺旋藻多糖(polysaccharides from Spirulina platensis,PSP)抗柯萨奇病毒B3(Coxsackie virus B3,CVB3)活性的研究.以不同剂量的PSP作用于病毒复制周期的各个环节,以病毒半数感染量(TCID50),细胞病变效应(CPE),蚀斑形成单位(PFU),MTT染色细胞保护率(MTT法)作为评价指标,判断PSP的抗病毒效果.结果表明PSP对Vero细胞毒性极低(TC50为1750μg/mL),对CVB3无直接灭活作用,PSP可干扰病毒向宿主细胞的吸附,其抗病毒生物合成的活性最高(IC50为5.26,TI为237.6),是阳性对照药病毒唑的3.95倍,但不影响病毒的释放.提示PSP抗病毒靶位可能在于抑制病毒吸附和感染细胞内病毒的生物合成.     

螺旋藻在光胁迫时的抗逆性研究

螺旋藻对于环境的变化有很强的适应性.以钝顶螺旋藻为实验材料,测定螺旋藻在受到较强光照胁迫时藻体的电导率以及脯氨酸、丙二醛和过氧化氢酶系的含量.在3000 lx光照下,螺旋藻6个藻株的电导率以及脯氨酸、丙二醛和过氧化氢酶系的含量比在1000 lx光照下明显升高,螺旋藻的电导率最高上升了2～6倍;细胞内的脯氨酸含量最多增加5倍,最少增加13%;丙二醛的含量增加40%～100%;过氧化氢酶的含量上升范围在19%～80%,过氧化物酶的含量上升范围在20%～100%.说明螺旋藻在受到光胁迫时自身会启动相关保护机制,产生一定的抗逆性,以适应环境的变化.     

倍频Nd：YAG激光对钝顶螺旋藻的诱变效应

利用倍频 Nd:YAG激光 (波长 53 2 nm,功率 50 0 m W,功率密度 1 60 m W/cm2 )诱变钝顶螺旋藻 ,辐照时间为 1 5min、1 0 min、5min通过测定藻丝形态参数、叶绿素 a、β 胡萝卜素、生长速度 ,比较倍频 Nd:YAG激光对钝顶螺旋藻生长的影响。实验结果表明 :与出发株相比 ,经倍频 Nd:YAG激光辐照后 ,藻丝形态发生变化 ,藻丝长、螺旋数、螺旋长变小 ;1 5min,1 0 min辐照组出现螺旋变松驰 ;1 0 min,5min辐照组促进藻的生长和叶绿素 a含量提高 ,使生长速度提高。三个诱变时间剂量都有利于 β 胡萝卡素积累 ,含量增幅最高达 2 2 .3 %。     

硒胁迫对钝顶螺旋藻抗氧化酶系统的影响

在钝顶螺旋藻的对数生长期进行硒胁迫处理,研究硒胁迫强度和硒胁迫时间对钝顶螺旋藻抗氧化酶系统与脂质过氧化作用的影响。设置4个胁迫实验组,分别从第5天到第10天分次加硒,累计加硒量均为1000 mg/L。结果表明,硒胁迫实验组中钝顶螺旋藻的抗氧化酶活性均高于对照组或与对照组相当,其中GPX的变化最大,实验组Ⅰ中的GPX活性为对照组的20.5倍;SOD的变化趋势与GPX相近,但对较低的硒胁迫的响应不敏感;POD、CAT和APX的活性均随硒胁迫强度的减小而上升;各硒胁迫实验组中只有实验组Ⅰ的MDA含量高于对照组;藻体对.OH的清除能力与藻体的MDA含量呈负相关,提示了硒对钝顶螺旋藻抗氧化系统的双重效应。     

Biotransformation of codeine to morphine in freely suspended cells and immobilized cultures of Spirulina platensis

Both freely suspended cells and immobilized cultures of Spirulina platensis, a blue-green alga, biotransformed exogenously fed codeine, an opium alkaloid, to morphine. The external addition of codeine to the culture medium did not affect the growth of S. platensis. Immobilization of Spirulina in a calcium alginate gel matrix was optimized by using 2% (w/v) sodium alginate and reducing the concentration of nutrients of Zarrouk's medium, which caused destabilization of the calcium alginate gel. The accumulation of morphine increased gradually and reached maxima of 330g 100ml^–1 culture at 105h in freely suspended and 351g 100ml^–1 at 96h in immobilized Spirulina cultures. Accumulation of morphine was detected only in the medium, whereas cells did not show accumulation. The immobilized Spirulina cultures showed marginally higher conversion of codeine to morphine over freely suspended cultures.     

Capacity of Spirulina platensis to accumulate manganese and its distribution in cell

Effects of manganese salt (MnCl₂) on growth of Spirulina platensis and capacity of the cyanobacteria to accumulate the metal in various cell components were studied. S. platensis cells were shown to tolerate high concentrations of manganese and preserve, although strongly suppressed, the capacity to grow in the medium containing 5.1 mM MnCl₂. The concentrations of manganese that did not inhibit growth considerably altered cell ultrastructure and changed the protein profile. The accumulation of manganese in S. platensis cells was proportional to the period of culturing and manganese concentration in the medium, reaching a plateau at about 2.5 mM. A threshold intracellular concentration of this metal is estimated as 28 ± 3 μmol/g dry wt. The fractionation of the manganese-enriched biomass demonstrated that the major portion of intracellular manganese (over 90%) was found in the total protein fraction. The chromatographic separation of the soluble protein fraction showed that manganese was incorporated into proteins with molecular weight of 5 to 15 kD. Dry biomass adsorbed manganese cations; this evidence seems to indicate a considerable contribution of biosorption to manganese accumulation by S. platensis cells.     

Competitiveness of Frankia strains on Elaeagnus clonal plantlets

Abstract Growth of the cyanobacterium Spirulina platensis , like that of many prokaryotic and eukaryotic organisms, is inhibited by low concentrations of valine, one of the three end-products of the branched-chain amino acid biosynthetic pathway. We assayed and partially characterized the activity of acetyhydroxy acid synthase (AHAS), the first common enzyme of the branched pathway in cell-free extracts from axenic S. platensis cultures. Assays performed at various pH values showed two peaks of activity, both inhibited by valine. FAD was not required for enzyme activity but protected it during dialysis. We also investigated whether the three amino acids were able to cause repression of AHAS synthesis and a significant drop in the enzyme-specific activity could be seen only when cultures were grown in the presence of valine. Chromatography on hydroxylapatite showed one single peak of activity.     

Harvesting of Spirulina platensis by cellular flotation and growth stage determination

AIM: To investigate an effective harvesting method for Spirulina platensis. METHODS AND RESULTS: Eighty per cent of S. platensis cells in the logarithmic growth phase were harvested by flotation when the cells were set in a static condition for 2 h. The optimum harvesting time was about day 6 of cultivation. The flotation activity of S. platensis cells was enhanced by the addition of NaCl. CONCLUSIONS: The harvesting of S. platensis by flotation is a cost-effective and straightforward method that can retain the algal quality. The optimum harvesting time of S. platensis can be predicted by the cellular protein to carbon ratio. SIGNIFICANCE AND IMPACT OF THE STUDY: Flotation harvesting is also applicable to other cyanobacteria with gas vesicles.     

Construction of a cosmid library of Spirulina platensis as an approach to DNA physical mapping

Abstract A Spirulina platensis gene library has been constructed using cosmid vector pMMB34. The cosmid bank was controlled for its random gene distribution by colony hybridization. Genes were identified using either homologous or heterologous probes of genes involved in photosynthesis (large and small subunit of d -ribulose 1,5-bisphosphate carboxylase, 32 kDa thylakoid protein, α, β subunits of C-phycocyanin) and protein synthesis (elongation factors EF-Tu, EF-G).