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。     

Use of chlorophyll fluorescence to estimate the effect of photoinhibition in outdoor cultures ofSpirulina platensis

Chlorophyll fluorescence measurements were used to evaluate the effect of temperature on photoinhibition inSpirulina platensis cultures grown in tubular reactors outdoors. Cultures grown at 35 °C during the day time showed a lower reduction in the Fv/Fm ratio as compared to cultures grown at 25 °C. It is demonstrated that the lower temperature photoinhibited cells can undergo a complete recovery once transferred to low light and higher temperature. This recovery does not take place when 100 µg ml^-1 chloramphenicol is added to cells. The recovery is light dependent and cells incubated in the dark at low temperature do not show a recovery in the Fv/Fm ratio. The data presented strongly support the hypothesis that photoinhibition takes place in outdoorSpirulina cultures. At the same time it is demonstrated that fluorescence measurements can be used as a fast reliable indication for photoinhibition in outdoor algal cultures.Author for correspondencePublication No. 69 of the Microalgal Biotechnology Laboratory.     

Far‐red dependent changes in the chemical composition of Spirulina platensis

The influence of far‐red light (FRL) was studied on the chemical composition of Spirulina platensis biomass. The following light compositions were used during the culture white light, blue‐red LED light (BRL) and BRL supplemented with FRL (BRFRL). Chlorophyll and phenol contents were measured by spectrophotometric methods, whereas presence of carotenoids, lipids, and phycobiliproteins were estimated by Fourier‐transform Raman spectrometry. Additionally, phenol content was investigated by fluorescence intensity of algae culture in the range of 430–650 nm. The content of chlorophyll and phenols in algae cells depended on the spectral composition of light and was the highest under BRL (16.7 ± 0.5 and 9.1 ± 0.6, respectively). It was shown that there is a positive linear correlation (R = 0.902 at p < 0.0000001) between the ratio of relative fluorescence intensity of S. platensis suspensions at 450 nm to the suspensions at 540 nm (F450/F540) and the content of phenolic compounds in the biomass. Changes in the F450/F540 ratio can explain approximately 80% changes of phenol contents in algae cells. Spirulina platensis Raman spectra demonstrated that the biomass of algae growing under white light and BRL had a significantly higher intensity of phycobiliprotein bands than the algae growing under BRFRL.     

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.     

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     

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 %。     

绿色荧光蛋白gfp基因在钝顶螺旋藻(Spirulina platensis)A9藻株中的表达

将钝顶螺旋藻(Spirulina platensis)A9藻株在24℃培养,经2 mmol/L的EDTA预处理24 h;采用功率300 W的超声波处理70 s获得单细胞样品,以本实验室构建的携带gfp基因的质粒p215t转化A9藻株单细胞藻液,利用Amp作为选择标记,使单细胞在平板上再生长出单藻落,获得17株具有Amp抗性的转化藻株,转化率3.73‰。在390 nm紫光激发下,生长30天的转化藻丝体发出稳定绿色荧光;培养45天后具有绿色荧光的藻丝出现断裂、具有荧光藻丝长度缩短的现象。实验结果初步表明:报告基因gfp在螺旋藻中得到稳定有效的表达,可以采用单细胞再生形成单藻落技术进行螺旋藻的基因克隆。     

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。     

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.     

Alterations in beta-islets of Langerhans in alloxan-induced diabetic rats by marine Spirulina platensis

Marine Spirulina platensis may potentially influence the metabolic process in animal cells, and the effect of marine Spirulina platensis in normal and alloxan-induced diabetic rats was therefore investigated. Normal and diabetic rats (albino Wistar strain) were orally administered marine Spirulina platensis for 30 days and their blood levels of glucose and insulin and body weight changes were determined. Pancreatic histopathology was also noted. Treatment with marine Spirulina platensis caused significant alterations in the content of these indicators and therefore in the antidiabetic capacity of the treated animals compared to control rats.     

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.     

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.     

Role of light and photosynthesis on the acclimation process of the cyanobacteriumSpirulina platensis to salinity stress

The response ofSpirulina platensis cells to salinity stress was studied. Once adapted to the higher osmoticum, photosynthetic parameters such as the maximum rate of photosynthesis under saturating irradiance (P_max) and the initial slope of the P-I curve () are reduced by 15% and 25% in 0.5 M NaCl grown cells, respectively. Salt-adapted cells have a modified biochemical composition; reduced protein and chlorophyll content, and an increased level of carbohydrates. The reduction in the photosynthetic capacity of the salt-adaptedSpirulina cells reflects a lower ability to utilize light energy and results in an increase in the susceptibility of the stressed cells to photoinhibition. This conclusion is supported by the finding that cultures exposed to salt stress show not only a decrease in growth rate (), but lose the ability to respond to increased irradiance with an increase in growth. The use of variable fluorescence as a fast and reliable measurement to follow the changes in PSII of salt-stressesSpirulina cells enables following the early events of salinity shock. It indicates that as soon as the cells are exposed to salt, a protection mechanism is induced. This mechanism does not require any protein synthesis and may take place even in the dark, though at somewhat reduced effectiveness. The significance of the result in providing a better understanding of the interaction between two environmental stresses — light and salinity — and their application in the outdoor mass cultivation ofSpirulina are discussed.Author for correspondence     

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。     

钝顶螺旋藻表面微观形貌的原子力显微镜研究

该文应用原子力显微镜(AFM)纳米级的分辨率对钝顶螺旋藻(Spirulina platensis)表面微观形貌进行了研究,获得了扫描范围为5.000×5.000μm、1.000×1.000μm和400.0×400.0nm三组清晰、稳定的图像,并对其进行了线性分析。结果表明:螺旋藻表面由紧密且无序堆积的突起结构组成,其高度小于20nm;突起结构高度从3nm~15nm不等,平均高度约为8~9nm。此法用于生物体表面,操作简单、快速、灵敏度好且样品无损伤,结果令人满意。     

Light and oxygen stress in Spirulina platensis (cyanobacteria) grown outdoors in tubular reactors

As the effects of light and oxygen stress in algae on mass culture has not been intensively studied, we investigated them in Spirulina platensis under outdoor conditions in controlled tubular reactors where the respective roles of each stress can be distinguished. It was observed that exposure of this cyanobacterium at two oxygen concentrations (ca 20 and 53 mg 1⁻¹) caused very little change in the ratio between variable and maximum fluorescence (F_v/F_m) during the day even when the culture was grown at higher oxygen concentration (about 7% lower in the evening than in the morning). Vice-versa, when the photochemical efficiency of PSII (photon yield, Φ_c) was measured, a reduction of about 20% was observed. Neither the F_v/F_m ratio nor the Φ_c of the culture grown at the lower oxygen concentration changed significantly during the day. The daily productivity of the culture exposed to the higher oxygen concentration was reduced by about 20%. Laboratory cultures bubbled with air or pure oxygen under continuous light showed a similar response; i.e., a smaller decrease in F_v/F_m (17%) than in the Φ_c (56%) after 4 h. After 32 h of culture in pure oxygen, a total lysis of the cells occurred. Our results support the hypothesis that photoinhibition and photooxidation, two traditionally linked terms, although often closely associated under similar environmental conditions, may comprise two types of stress with different sites of inhibition.     

不同生境下的钝顶螺旋藻RAPD分析

本文对不同生境下的钝顶螺旋藻Spirulina(Arthrospira)platensis进行了RAPD分析.结果表明,鄂尔多斯高原碱湖和Chad湖的钝顶螺旋藻基因组DNA扩增多态性片段同源性为48.23%.2个样品在分子遗传水平上存在着较大的差异,这是由于各自生态环境明显不同和长期地理隔离造成的.     

不同生境下的钝顶螺旋藻RAPD分析

本文对不同生境下的钝顶螺旋藻Spirulina (Arthrospira) platensis进行了RAPD分析。结果表明, 鄂尔多斯高原碱湖和Chad湖的钝顶螺旋藻基因组DNA扩增多态性片段同源性为 48.23%。2 个样品在分子遗传水平上存在着较大的差异, 这是由于各自生态环境明显不同和长期地理隔离造成的。