用于微藻培养的气升式光生物反应器

基于微藻光自养培养特性 ,构建了具有较大面积体积比的 15 L内外光源相结合的气升式光生物反应器 ,考察了两种不同形态藻细胞培养体系中 ,光强随细胞浓度及光程距离衰减的规律 ,得到了描述光衰减的数学关系式 ,即在鱼腥藻 712 0培养体系中为 I=I0 exp[- (0 .0 131+0 .987OD750 )·L],在聚球藻 70 0 2培养体系中为 I=I0 exp[- (- 0 .0 2 39+0 .0 777OD750 )·L],并据此对培养过程中光强沿反应器径向的动态分布情况进行了估算。在该反应器中进行了鱼腥藻 712 0和聚球藻 70 0 2两种蓝藻的光自养培养 ,藻细胞培养终密度分别达到 1.5 3g/ L和 3.4g/ L ,体积产率分别为 0 .31g L-1d-1和 0 .5 7g L-1d-1,说明该反应器适合于微藻的高密度培养     

能源微藻开发利用的研究

微藻与陆生作物相比,具有生物量大、生长周期短、脂质含量高、不占耕地、单位面积产出量高等特点,已成为生物柴油原料的首选。微藻生物燃油的经济性大规模生产,需要建立能保持单一藻种优势的微藻规模化生产系统。但现有的微藻生产生物柴油的工业化模式与商业应用目标还有很大差距。本文讨论了能源微藻开发利用技术的热点问题,综述了国内外能源微藻开发现状及存在的问题。     

环氧树脂涂层表面亲水性对微藻黏附性能的影响

在固体材料表面黏附成膜是微藻细胞的一种生理特性。近些年基于微藻生物膜的生物过程,如生物膜贴壁培养和防附着技术受到了很多关注。微藻在固体材料表面的黏附受藻细胞与材料表面之间的相互作用的影响,建立黏附强度与材料表面性质参数间的关系对于通过材料选择来强化或控制微藻生物膜具有非常重要的意义。本工作的目的是揭示和明确材料亲疏水性对微藻黏附的影响,提出了一种双酚A环氧(EP)树脂表面亲疏水改性的方法。通过将亲水性的二乙醇胺(DEA)或疏水性的聚甲基聚硅氧烷(PMHS)加入到EP树脂中反应,EP树脂表面水接触角在36.80?~98.34?范围内可通过加入不同量的DEA或PMHS实现任意可调,材料的表面水接触角与DEA或PMHS加入量之间有线性关系。重要的是这种改性方法获得的材料,其形貌、结构、表面粗糙度等表面性质几乎没有变化,从而在研究和关联微藻黏附量与材料表面亲疏水性(表面水接触角)之间的关系时可以排除亲疏水性之外的其他表面性质的影响;其次,考察了小球藻和栅藻在不同亲疏水性材料表面的黏附行为,结果表明小球藻和栅藻在亲水性和疏水性材料表面均能黏附成膜,但在亲水性材料表面黏附更多更快;建立了微藻最大黏附容量与材料表面接触角之间关联关系,表明微藻最大黏附容量随材料表面水接触角的增大而线性降低,栅藻的表面黏附容量比小球藻大。     

微藻培养光生物反应器内传递现象的研究进展

微藻规模化培养过程中光生物反应器内传递现象是影响微藻的生长及产量的重要因素。本文重点综述了光生物反应器内传递现象（光传递、传热、传质和传动量传递）及其数学模型研究进展,分析了光生物反应器结构和尺寸对光传递和传质的影响,总结影响各传递现象的重要参数,如光吸收系数、体积传质系数等,为高效光生物反应器的设计、优化及放大提供了参考依据。     

+UVA treatment increases the degree of unsaturation in microalgal fatty acids and total carotenoid content in Nitzschia closterium (Bacillariophyceae) and Isochrysis zhangjiangensis (Chrysophyceae)

The production of metabolites by microalgae is affected by environmental conditions in which they are living. The metabolic responses of two marine microalgae, Nitzschia closterium and Isochrysis zhangjiangensis, to a 3-day UVA-stress and 3-day UVA-recovery treatment were compared, based on their growth, fatty acid profiles and content of total carotenoids. When cultured under photosynthetically active radiation, coupled with UVA treatment, both microalgae underwent a significant increase in their growth during the UVA-recovery period compared to the control. The proportions of polyunsaturated fatty acids, including linoleic acid and eicosapentaenoic acid, as well as total carotenoids, were significantly increased in both microalgae, mainly in the UVA-stress period, but not the UVA-recovery period. The metabolic responses of the two microalgae to UVA treatment were species-dependent and could be utilised to produce microalgal biomass rich in polyunsaturated fatty acids and carotenoids for use as functional food ingredients.     

氮浓度对异养小球藻生长及蛋白质含量的影响

为了提高异养小球藻蛋白质含量低的问题,研究了异养小球藻生长及蛋白质含量和氮浓度的关系,探究了分阶段调控氮浓度对异养小球藻生长及蛋白质含量的影响。结果表明,氮浓度在3～15mmol/L范围内,小球藻生物量及蛋白质含量随氮浓度增加而增加,生物量从0.91g/L提高到了3.02g/L,蛋白质含量从26.1%提高到了37.4%。分阶段培养小球藻,首先在低氮条件下培养至指数期前期,然后转移至高氮浓度下培养,生物量达3.04g/L,且蛋白质含量提高至53.8%,与自养培养条件下蛋白质含量相当。     

Daily doses of light in relation to the growth of Scenedesmus obliquus in diluted three‐phase olive mill wastewater

BACKGROUND: The use of olive‐oil mill wastewater (OMW) from a three‐phase centrifugation process used in the olive‐oil industry, has been studied in relation to the production of the microalga Scenedesmus obliquus CCAP 276/3A. The chemical characteristics of OMW indicated nitrogen deficiency. RESULTS: S. obliquus is able to assimilate nutrients present in a culture medium (water‐OMW 5%) and grow at its maximum specific growth rate of 0.026 h^?1, both under mixotrophic as well as heterotrophic conditions. The different daily doses of light (DDL) used, in the range 0–36 E m^?2 d^?1, determined light‐limited and light‐inhibited cultures. The light‐inhibited mixotrophic cultures bore characteristics similar to those of the heterotrophic cultures, and became more so when the dose of light received was higher. The low protein yield (258 mg g^?1) and high percentage of carbohydrates of the biomass (65.8%) confirmed a nutritional‐stress situation associated with nitrogen limitation. CONCLUSION: The similarity between the fatty‐acid composition of the heterotrophic and mixotrophic cultures strongly inhibited by light appeared to indicate the cancelling of the photosynthetic behaviour of the cells at high DDL values. The biomass generated can be used for biofuels. The maximum elimination of biological oxygen demand (BOD₅) per unit of biomass was achieved in the heterotrophic cultures. Copyright © 2009 Society of Chemical Industry     

Clarification of suspensions by colloidal gas aphrons

Colloidal gas aphrons (CGAs), generated from dilute solutions of four surfactants, were used to clarify palm oil mill effluent (POME), suspensions of microalgae and suspensions of three inorganic minerals. In POME and the algal suspensions, each CGA was most effective at a pH value close to the pK value of the surfactant concerned. This effect was not tested in the inorganic suspensions. The efficiency of air utilization was directly related to the concentration of solids in the suspensions, the size, density and nature of the solids having secondary effects. Comparison with data in the literature led to a general correlation embracing a variety of suspensions and flotation systems. Shedding of collected material from the foam layer was also a direct function of solids concentration. CGAs offer advantages over other systems of air-assisted flotation in relation to the requirements for equipment and to the management of process operations.     

Rapid Characterization of Fatty Acids in Oleaginous Microalgae by Near-Infrared Spectroscopy

The key properties of microalgal biodiesel are largely determined by the composition of its fatty acid methyl esters (FAMEs). The gas chromatography (GC) based techniques for fatty acid analysis involve energy-intensive and time-consuming procedures and thus are less suitable for high-throughput screening applications. In the present study, a novel quantification method for microalgal fatty acids was established based on the near-infrared spectroscopy (NIRS) technique. The lyophilized cells of oleaginous Chlorella containing different contents of lipids were scanned by NIRS and their fatty acid profiles were determined by GC-MS. NIRS models were developed based on the chemometric correlation of the near-infrared spectra with fatty acid profiles in algal biomass. The optimized NIRS models showed excellent performances for predicting the contents of total fatty acids, C16:0, C18:0, C18:1 and C18:3, with the coefficient of determination (R²) being 0.998, 0.997, 0.989, 0.991 and 0.997, respectively. Taken together, the NIRS method established here bypasses the procedures of cell disruption, oil extraction and transesterification, is rapid, reliable, and of great potential for high-throughput applications, and will facilitate the screening of microalgal mutants and optimization of their growth conditions for biodiesel production.