LED光质调控微藻生长及目标产物积累的研究进展

光是影响微藻光自养生长的最重要因素.LED光质在调控微藻生长及目标产物积累方面的巨大优势已经引起了诸多研究者及相关企业的高度重视.基于LED光质调控技术开发的微藻培养工艺有望革新现有生产技术,促进微藻产业的快速发展.为此,本文阐述了微藻可吸收利用的光谱范围及光受体、不同LED光质对微藻生长及目标产物积累的影响、基于LE...     

经济微藻高密度培养技术及其生物资源化利用

经济微藻富含不饱和脂肪酸、蛋白质、碳水化合物等多种生物活性物质, 可以应用于食品加工业、水产养殖业、医药与美容业、废水处理环保业和生物能源业等各行业。开发和利用微藻生物资源将是解决人类能源需求的重要途径, 微藻产业化的发展进程与社会经济、生态环境和人类健康有密切的关系。微藻高密度培养是提高微藻生物质产量和活性代谢产物, 发展生物质能源的关键环节。论文综述了微藻的社会经济价值, 指出了其在能源、食品、水产等行业的重要作用; 介绍了开放式培养和封闭式培养的两大类技术体系, 比较分析了柱状光反应器、平板光反应器和管状光反应器的特点; 概括了影响经济微藻生长和油脂含量的主要因素, 包括光照、温度、pH、营养元素等, 最后展望了经济微藻培养及其生物资源化利用的前景。     

利用废水培养微藻的研究进展

微藻被认为是一种有潜力的、可被开发为再生能源的重要生物材料。一些微藻种类具有较强的异养和混养能力,能直接利用有机物作为碳源。工农业生产和城市生活中所排放的废水中通常含有大量的有机碳、氮、磷等营养物质。利用废水培养微藻,一方面可以将废水中的碳、氮、磷等营养物质转化为具有更高价值的微藻生物质,另一方面又可实现废水的净化和营养物质的再利用。本综述了不同种类废水的特点,讨论了两类微藻培养模式的优劣,同时还探讨了微藻对营养元素的利用,并总结了微藻培养需突破的瓶颈。     

微藻生物质成分检测方法评述

不断发展的微藻产业需要统一可信的生物质检测方法体系来评估微藻研究、培养及生产中的各种生物质指标。对目前常用的微藻生物质组成的检测方法进行综述及评估,以期推动微藻产业的生物质分析平台标准化。     

微藻规模培养技术研究进展

产油微藻是最具潜力的生物能源油脂资源之一,有关微藻生物能源的技术研究开发近年来受到国内外持续重视。微藻能源生产是一个涉及到从藻种、规模培养技术与装备,到能量转化加工全产业链的复杂过程,其中以解决微藻生物量资源的规模培养是整个产业过程的核心。从微藻的产能潜力分析出发,对微藻的光自养与异养模式以及微藻的开放池和光反应器培养研究进展进行了总结,特别分析了近些年发展起来的微藻序贯式异养—稀释—光诱导和贴壁培养技术等。并对涉及微藻培养的相关技术包括光能利用、水源和二氧化碳源解决,以及污染及其控制研究进展进行了分析。在此基础上,提出微藻规模培养必须以高效抗逆工业性状和高值化学品联产特色藻种的选育,与装备创新为重点和突破口,并将废气/废水等利用与规模培养相结合,从而构建起与环境处理相耦联的微藻能源—高值化学品多联产产业技术体系。     

基于文献计量的微藻收获技术研究分析

微藻是能以自养模式固定二氧化碳,生成生物能源的原料,对可持续发展具有重要意义。微藻也能以异养模式生长,用于废水处理和积累高附加值物质。目前,微藻收获的成本占总成本的20%~30%。微藻收获技术已经成为研究热点。本文从文献计量的角度分析了各国微藻收获的研究进展以及我国的研究现状,并展望了微藻收获技术发展趋势,为进一步研究提供参考。     

产生物柴油微藻培养研究进展

石油的大量使用会导致能源枯竭和温室气体（CO2）排放的增加。为了实现经济和环境的和谐发展,必须使用可再生能源代替石油。可再生能源使用后不会造成温室气体排放的增加。生物柴油是一种理想的可再生能源, 能满足以上要求,所以近年来得到迅速发展。微藻是一种主要利用太阳能固定 CO2,生成制备生物柴油所需油脂的藻类。因此以微藻油脂为原料转化成的生物柴油是石油理想的替代品。简要介绍了产油微藻的种类和微藻油脂的合成,较详细地阐述了微藻自养培养、异养培养、生物反应器、工程微藻的最新研究进展,并初步展望了微藻产油研究的未来发展方向。     

微藻生物质产品和生物活性物质的研究与开发

本文综述了微藻在生物质产品及活性物质开发上的研究进展。部分微藻如节旋藻、小球藻、盐生杜氏藻和雨生红球藻等已用于商业化生产生物质产品。另外,从微藻中提炼的生物活性成分如β-胡萝卜素、虾青素、藻蓝蛋白、长链多不饱和脂肪酸和活性多糖等已应用于营养保健品和化妆品的生产。基于微藻种类的多样性和基因工程、代谢工程的快速发展,微藻天然产物具有很大的开发潜力。     

微藻两阶段培养技术研究进展

微藻细胞富含油脂、淀粉及其他高值代谢物,可用于食品、饲料、化学品和能源的生产。但在规模化培养中,微藻的高生长速率和高产物含量难以兼得,制约了其商业化应用。通过微藻的两阶段培养技术可以将生长和产物积累的时期分离,从而同时获得较高的微藻生物量和产物含量。该技术具有产品得率高、节能减排、适用范围广的优点,是推进微藻商业化的关键之一。本综述总结了现有微藻两阶段培养技术的优势和产品类型,解析了目前微藻两阶段培养技术的限制因素及发展前景,并提出微藻两阶段培养中存在阶段转换时间尚不明确、中间采收步骤成本高这两个限制该技术应用的关键瓶颈,从而为未来微藻两阶段培养技术规模化生产方案的科学决策与实施提供参考。     

微藻生物燃料及高价值产物的代谢研究进展

微藻是当今代谢工程领域最具潜力的燃料生物质来源之一.其结构简单、基因可操作性强的特点使其可通过不同的代谢工程手段得到丰富多样的生物燃料和高价值产物.本文系统地总结了近年来国内外利用微藻在脂质、氢气、乙烯、醇类、脂肪醇和脂肪烃、糖类、萜类及其他高价值产物的生产中取得的进展,并通过介绍着眼于改变光合作用关键酶体或复合物以提升生物质产量的相关研究进展,分析了生物质合成代谢途径的改变对上游光合作用的潜在影响.结合系统生物学及生物信息学方法筛选高效的微藻株系,改变碳流方向以提升生物质的合成效率,实现高效地同源重组,提高外源基因在微藻内的表达效率是微藻代谢工程亟待解决的问题.本文在此基础上结合近年来各个交叉学科的发展趋势,提出了若干改良微藻代谢的新模式,以期对微藻代谢研究及后续的工程改造有所启示.     

Cultivation, photobioreactor design and harvesting of microalgae for biodiesel production: A critical review

Microalgae have the ability to mitigate CO₂ emission and produce oil with a high productivity, thereby having the potential for applications in producing the third-generation of biofuels. The key technologies for producing microalgal biofuels include identification of preferable culture conditions for high oil productivity, development of effective and economical microalgae cultivation systems, as well as separation and harvesting of microalgal biomass and oil. This review presents recent advances in microalgal cultivation, photobioreactor design, and harvesting technologies with a focus on microalgal oil (mainly triglycerides) production. The effects of different microalgal metabolisms (i.e., phototrophic, heterotrophic, mixotrophic, and photoheterotrophic growth), cultivation systems (emphasizing the effect of light sources), and biomass harvesting methods (chemical/physical methods) on microalgal biomass and oil production are compared and critically discussed. This review aims to provide useful information to help future development of efficient and commercially viable technology for microalgae-based biodiesel production.     

Heterotrophic cultivation of microalgae for production of biodiesel

High cell density cultivation of microalgae via heterotrophic growth mechanism could effectively address the issues of low productivity and operational constraints presently affecting the solar driven biodiesel production. This paper reviews the progress made so far in the development of commercial-scale heterotrophic microalgae cultivation processes. The review also discusses on patentable concepts and innovations disclosed in the past four years with regards to new approaches to microalgal cultivation technique, improvisation on the process flow designs to economically produced biodiesel and genetic manipulation to confer desirable traits leading to much valued high lipid-bearing microalgae strains.     

Ultrahigh-cell-density heterotrophic cultivation of the unicellular green microalga Scenedesmus acuminatus and application of the cells to photoautotrophic culture enhance biomass and lipid production

Although production of biodiesels from microalgae is proved to be technically feasible, a commercially viable system has yet to emerge. High-cell-density fermentation of microalgae can be coupled with photoautotrophic cultivation to produce oils. In this study, by optimizing culturing conditions and employing a sophisticated substrate feed control strategy, ultrahigh-cell-density of 286 and 283.5 g/L was achieved for the unicellular alga Scenedesmus acuminatus grown in 7.5-L bench-scale and 1,000-L pilot-scale fermenters, respectively. The outdoor scale-up experiments indicated that heterotrophically grown S. acuminatus cells are more productive in terms of both biomass and lipid accumulation when they are inoculated in photobioreactors for lipid production as compared to the cells originally grown under photoautotrophic conditions. Technoeconomic analysis based on the pilot-scale data indicated that the cost of heterotrophic cultivation of microalgae for biomass production is comparable with that of the open-pond system and much lower than that of tubular PBR, if the biomass yield was higher than 200 g/L. This study demonstrated the economic viability of heterotrophic cultivation on large-scale microalgal inocula production, but ultrahigh-productivity fermentation is a prerequisite. Moreover, the advantages of the combined heterotrophic and photoautotrophic cultivation of microalgae for biofuels production were also verified in the pilot-scale.     

Heterotrophic cultivation of microalgae for pigment production: A review

Pigments (mainly carotenoids) are important nutraceuticals known for their potent anti-oxidant activities and have been used extensively as high end health supplements. Microalgae are the most promising sources of natural carotenoids and are devoid of the toxic effects associated with synthetic derivatives. Compared to photoautotrophic cultivation, heterotrophic cultivation of microalgae in well-controlled bioreactors for pigments production has attracted much attention for commercial applications due to overcoming the difficulties associated with the supply of CO₂ and light, as well as avoiding the contamination problems and land requirements in open autotrophic culture systems. In this review, the heterotrophic metabolic potential of microalgae and their uses in pigment production are comprehensively described. Strategies to enhance pigment production under heterotrophic conditions are critically discussed and the challenges faced in heterotrophic pigment production with possible alternative solutions are presented.     

Integration of biological waste conversion and wastewater treatment plants by microalgae cultivation

In this study, growth performance and lipid content of two microalgae species Neochloris oleoabundans and Chlorella vulgaris are monitored by using three different types of sludge waste feedstocks obtained from the water treatment plants located in Bedonia, Borgotaro and Fornovo (Montagna2000 Spa, Province of Parma, Italy). The sludge waste is optimized in order to achieve microalgal growth media and dispose of the sewage sludge produced at the wastewater treatment facilities. Both photoautotrophic and heterotrophic growth conditions are applied to the microalgal cultivations. The growth parameters of microalgae strains such as cell concentration, growth rate, optical density, cell biovolume, photosynthetic pigments and lipid contents are monitored. The amounts of total dried lipid biomass, obtained by the biological conversion of the wet sludge waste, are determined. Lipid production of microalgal cells grown in the medium optimized from sludge waste from the Fornovo site provides the highest amount of microalgal lipid content for N. oleoabundans and C. vulgaris photoautotrophic cultivations, while sludge waste from the Bedonia site provides for N. oleoabundans heterotrophic cultivation.     

Microalgae: a robust “green bio-bridge” between energy and environment

Microalgae are a potential candidate for biofuel production and environmental treatment because of their specific characteristics (e.g. fast growth, carbon neutral, and rich lipid accumulations). However, several primary bottlenecks still exist in current technologies, including low biomass conversion efficiency, bio-invasion from the external environment, limited or costly nutrient sources, and high energy and capital input for harvest, and stalling its industrial progression. Coupling biofuel production with environmental treatment renders microalgae a more feasible feedstock. This review focuses on microalgae biotechnologies for both bioenergy generation and environmental treatment (e.g. CO₂ sequestration and wastewater reclamation). Different intelligent technologies have been developed, especially during the last decade, to eliminate the bottlenecks, including mixotrophic/heterotrophic cultivation, immobilization, and co-cultivation. It has been realized that any single purpose for the cultivation of microalgae is not an economically feasible option. Combinations of applications in biorefineries are gradually reckoned to be necessary as it provides more economically feasible and environmentally sustainable operations. This presents microalgae as a special niche occupier linking the fields of energy and environmental sciences and technologies. The integrated application of microalgae is also proven by most of the life-cycle analysis studies. This study summarizes the latest development of primary microalgal biotechnologies in the two areas that will bring researchers a comprehensive view towards industrialization with an economic perspective.     

以异养细胞作为种子的椭圆小球藻产油脂光自养培养优化

异养细胞种子/光自养培养方法是一种可异养培养的能源微藻培养的有效方法,但已有文献尚未从工艺优化角度考察其发展潜力。为了获得较高细胞密度的用于光自养培养的种子和提高光自养培养的细胞密度与油脂产率,对异养细胞种子/光自养培养的培养基和培养条件进行了优化。结果表明,采用优化后的培养基,椭圆小球藻在摇瓶中异养培养的最高藻细胞密度可达11.04 g/L,比在初始培养基条件下提高了28.0%,在5 L发酵罐中异养培养的藻细胞密度达到73.89 g/L;在2 L柱式光生物反应器中光自养培养的藻细胞密度、油脂含量和油脂产率分别达1.62 g/L、36.34%和6.1 mg/(L·h),油脂成分主要为含C16-C18碳链的脂肪酸,是制备生物柴油的理想原料。经过优化,异养细胞种子/光自养培养这一方法能够显著地提高椭圆小球藻产油脂的能力,这进一步表明异养细胞种子/光自养培养方法有望成为可异养的能源微藻的高效培养方式。     

Best practices in heterotrophic high-cell-density microalgal processes: achievements,potential and possible limitations

Microalgae of numerous heterotrophic genera (obligate or facultative) exhibit considerable metabolic versatility and flexibility but are currently underexploited in the biotechnological manufacturing of known plant-derived compounds, novel high-value biomolecules or enriched biomass. Highly efficient production of microalgal biomass without the need for light is now feasible in inexpensive, well-defined mineral medium, typically supplemented with glucose. Cell densities of more than 100 g l⁻¹ cell dry weight have been achieved with Chlorella, Crypthecodinium and Galdieria species while controlling the addition of organic sources of carbon and energy in fedbatch mode. The ability of microalgae to adapt their metabolism to varying culture conditions provides opportunities to modify, control and thereby maximise the formation of targeted compounds with non-recombinant microalgae. This review outlines the critical aspects of cultivation technology and current best practices in the heterotrophic high-cell-density cultivation of microalgae. The primary topics include (1) the characteristics of microalgae that make them suitable for heterotrophic cultivation, (2) the appropriate chemical composition of mineral growth media, (3) the different strategies for fedbatch cultivations and (4) the principles behind the customisation of biomass composition. The review confirms that, although fundamental knowledge is now available, the development of efficient, economically feasible large-scale bioprocesses remains an obstacle to the commercialisation of this promising technology.     

Microalgal feeds for aquaculture

The concurrent trends of increasing consumption of seafood and decreasing natural harvests will dictate that a larger portion of seafood must be derived from aquaculture in the 21st century. The difficulty of producing economically large quantities of microalgal feeds is currently one of the major impediments to the further development of the aquaculture industry. Traditional methods, which rely on photosynthetic growth in outdoor ponds or indoors under artificial lights, suffer from the phenomenon of light-limitation of biomass density. Certain species of microalgae are capable of heterotrophic growth to high density utilizing sugars or other organic compounds for energy and cell carbon. This paper reviews work with strains of heterotrophic algae that have demonstrated potential as both nutritional feeds and for economical production by fermentation.     

Microalgae for high-value compounds and biofuels production: A review with focus on cultivation under stress conditions

Microalgal biomass as feedstock for biofuel production is an attracting alternative to terrestrial plant utilization for biofuels production. However, today the microalgal cultivation systems for energy production purposes seem not yet to be economically feasible. Microalgae, though cultivated under stress conditions, such as nutrient starvation, high salinity, high temperature etc. accumulate considerable amounts (up to 60–65% of dry weight) of lipids or carbohydrates along with several secondary metabolites. Especially some of the latter are valuable compounds with an enormous range of industrial applications. The simultaneous production of lipids or carbohydrates for biofuel production and of secondary metabolites in a biorefinery concept might allow the microalgal production to be economically feasible. This paper aims to provide a review on the available literature about the cultivation of microalgae for the accumulation of high-value compounds along with lipids or carbohydrates focusing on stress cultivation conditions.