微藻光生物水解制氢技术

氢气是未来人类社会可持续发展的理想能源。介绍微藻太阳能光生物水解制氢的研究现状,重点讨论微藻光水解制氢的生物学原理。重点讨论微藻光解水制氢的酶学机理、工艺过程以及当前的主要研究方向。通过比较微藻固氮酶制氢、可逆产氢酶直接光水解制氢、可逆产氢酶间接光水解制氢等技术路线的优缺点,指出利用微藻可逆产氢酶两步法间接光水解制氢最具发展潜力,可望为21世纪的“氢能经济社会”提供大量的氢源。该技术成功的关键在于相关的基因工程和代谢调控研究取得重大突破。     

绿藻高效制氢影响因素的研究

绿藻作为生物能源的研究和开发具有诱人的发展前景。本文概述了绿藻制氢和产氢途径的研究进展,重点介绍了绿藻高效制氢的影响因素--绿藻[Fe]-氢化酶的研究和绿藻制氢的重要控制参数,同时,对绿藻制氢作为生物能源的开发应用前景进行了展望。     

生物质制氢技术研究进展

氢能以其清洁,来源广泛及用途广等优点成为最有希望的替代能源之一,用可再生能源制氢是氢能发展的必然趋势。由于生物质制氢具有一系列独特的优点,它已成为发展氢经济颇具前景的研究领域之一。生物质制氢技术可以分为两类,一类是以生物质为原料利用热物理化学方法制取氢气,如生物质气化制氢,超临界转化制氢,高温分解制氢等热化学发制氢,以及基于生物质的甲烷、甲醇、乙醇的化学重整转化制氢等;另一类是利用生物转化途径转换制氢,包括直接生物光解,间接生物光解,光发酵,光合异养细菌水气转移反应合成氢气,暗发酵和微生物燃料电池等技术。本文综述了目前主要的生物质制氢技术及其发展概况,并分析了各技术的发展趋势。     

绿藻光合生物制氢技术进展

氢能作为可再生、环境友好的能源,已成为营造可持续发展的经济节约型社会的理想能源。绿藻因能利用光能分解水产氢,被称为最有应用前景的方法之一。本文将综述绿藻光合产氢的原理,介绍该生物制氢技术的研究现状和最新进展,并对其发展趋势做以展望。     

暗发酵-光发酵两阶段联合生物制氢技术研究进展

随着能源紧缺的日益加剧,以及化石燃料燃烧引起的环境问题逐渐突显,氢能作为一种清洁可再生能源越来越受到青睐。生物制氢与热化学及电化学制氢相比其反应条件温和、低耗、绿色,是一项非常有应用前景的技术。生物制氢从广义上可以分为暗发酵和光发酵产氢两种,其中暗发酵微生物可以利用有机废弃物产生氢气以及有机酸等副产物,光合细菌在光照和固氮酶的作用下可以将暗发酵产生的有机酸继续用于产氢,因此两种发酵产氢方式相结合可以提高有机废物的资源化效率。将近年来暗发酵-光发酵两阶段生物制氢技术进行整理分析,从其产氢机理、主要影响因素、暗发酵-光发酵产氢结合方式(两步法、混合培养产氢)几个方面进行阐述,最后指出该技术面临的挑战。     

光合细菌产氢因子的研究进展

光合细菌在固氮的同时盘旋氢气,产氢与固氮是同步进行的。固氮与氢醇共同影响光合细菌的产氢活性,而外源生理条件又影响着固氮酶与氢酶的活性,其中有机碳阻抑吸氢酶表达,促进产氢;氨则抑制固氮活性而降低产氢量;氧气的存在使固氮酶与氢酶都失活,从而抑制放氢反应的进行。     

光合细菌光合产氢的研究进展

光合细菌 (Photosyntheticbacteria ,PSB)光合产氢的研究是国内外普遍关注的热点问题。就PSB光合产氢的机理、条件及光合细菌生态应用等方面进行综述 ,并着重论述了光合细菌产氢过程中两种主要的酶—固氮酶和氢酶以及影响酶活性的因素。     

联合生物制氢方法及发展趋势

为了在生物制氢过程中最大限度提高产氢量和产氢速率,增大底物的利用率以及更好地发挥菌种间的协同作用,联合生物制氢技术成为近年来人们关注的焦点。综述了目前国内外几种联合生物制氢方法的研究现状。并从产氢机理的角度对几种联合制氢技术进行了分析比较,重点强调光合发酵和暗发酵联合生物制氢技术具有广泛的发展前景,并指出其存在的问题和未来的发展趋势。     

不同固氮条件下蓝藻氢酶活性的研究

一般认为仅是原核生物才具有的氢酶,在一系列的光合和非光合固氮生物中也相继被发现。它在这些生物机体中执行着除固氮酶和可逆性氢酶(reversible hydrogenase)放氢以外的催化氢代谢的功能,并能回收固氮酶放氢中失去的氢,提高固氮效率,从而和     

光合菌生物制氢技术

简要分析了光合细菌产氢的主要影响因素,介绍了国内外光合细菌生物制氢技术的研究和应用现状,并对光合制氢技术的发展趋势和应用前景进行了评述。     

关于生物制氢

简述了生物制氢发展过程及现今取得的成果。经济发展和人类对能源需求造成了诸如环境污染、常规能源短缺等一系列问题。因此 ,作为一种新型、可再生能源 ,氢能研究已经受到了人们高度重视。与其它制氢方法相比 ,生物制氢有着突出的优点 ,尤其是藻类利用太阳能光解水制氢 ,使人们看到了解决能源问题的希望。     

Photoevolution of hydrogen during oxygenic photosynthesis of cyanobacteriumNostoc muscorum

Summary Nitrogen fixing cultures of the cyanobacteriumNostoc muscorum lacked hydrogen evolution but cultures infected with cyanophage N-1 showed significant hydrogen evolution and inactive nitrogenase, suggesting that nitrogenase activity is not responsible for the observed oxygen-resistant photoproduction of hydrogen. Significant oxygen-resistant hydrogen production by nitrate or ammonium assimilating cultures deficient in both nitrogenase and uptake hydrogenase activity supports this conclusion. These findings suggest a role of uptake hydrogenase in blocking the production of hydrogen during aerobic photosynthetic conditions.     

Hydrogen metabolism of three unicellular nitrogen-fixing cyanobacteria

Abstract The enzyme activities responsible for the evolution and consumption of hydrogen in three unicellular cyanobacteria were investigated. Gloeothece sp. 6909 and Cyanothece sp. 7822 performed an oxygen-tolerant nitrogen fixation, whereas the nitrogenase activity of Synechococcus sp. 7425 was much more sensitive to oxygen. While in Gloeothece the net hydrogen production during nitrogen fixation was relatively low due to recycling by an uptake hydrogenase, little hydrogen consumption was detected in Cyanothece and Synechococcu . On the other hand a reversible hydrogenase was demonstrated in the latter strains. However, only Cyanothece shows hydrogenase-catalysed hydrogen production in vivo under anaerobic conditions in the dark. It is suggested that hydrogen is a fermentation product, and that the physiological function of this reversible hydrogenase is the removal of excess reduction equivalents under such conditions.     

Photoproduction of hydrogen, nitrogenase and hydrogenase activities of free and immobilized whole cells of Rhodobacter sphaeroides O.U. 001

Abstract Photoproduction of hydrogen, nitrogenase activity (acetylene reduction) and hydrogenase activity (methylene blue dye reduction) were studied in free and alginate immobilized whole cells of a purple non-sulfur photosynthetic bacterium Rhodobacter sphaeroides O.U. 001. Four-fold increase in hydrogen production, two-fold increase in nitrogenase activity and 1.2-fold increase in the hydrogenase activity were observed in immobilized cells compared to free cells. Effect of various inhibitors (CO and C₂H₂) and electron donor (H₂) on the above three functions by free and immobilized cells has also been studied.     

Acclimation of green algae to sulfur deficiency: underlying mechanisms and application for hydrogen production

Hydrogen is definitely one of the most acceptable fuels in the future. Some photosynthetic microorganisms, such as green algae and cyanobacteria, can produce hydrogen gas from water by using solar energy. In green algae, hydrogen evolution is coupled to the photosynthetic electron transport in thylakoid membranes via reaction catalyzed by the specific enzyme, (FeFe)-hydrogenase. However, this enzyme is highly sensitive to oxygen and can be quickly inhibited when water splitting is active. A problem of incompatibility between the water splitting and hydrogenase reaction can be overcome by depletion of algal cells of sulfur which is essential element for life. In this review the mechanisms underlying sustained hydrogen photoproduction in sulfur deprived C. reinhardtii and the recent achievements in studying of this process are discussed. The attention is focused on the biophysical and physiological aspects of photosynthetic response to sulfur deficiency in green algae.     

Nitrogen Fixation by Thermophilic Blue-Green Algae (Cyanobacteria): Temperature Characteristics and Potential Use in Biophotolysis

Thermophilic, nitrogen-fixing, blue-green algae (cyanobacteria) were investigated for use in biophotolysis. Three strains of Mastigocladus laminosus were tested and were found to be equally effective in biophotolysis as judged by nitrogenase activity. The alga, M. laminosus NZ-86-m, which was chosen for further study, grew well in the temperature range from 35 to 50°C, with optimum growth at 45°C, at which temperature acetylene reduction activity was also greatest. The maximum tolerable temperature was 55°C. Acetylene reduction activity was saturated at a light intensity of 1 × 10⁴ ergs cm⁻² s⁻¹. Atmospheric oxygen tension was found to be slightly inhibitory to acetylene reduction of both slowly growing and exponentially growing cultures. Nonsterile continuous cultures, which were conducted to test problems of culture maintenance, could be operated for 2 months without any significant decrease in nitrogenase activity or contamination by other algae. Nitrogen-starved cultures of M. laminosus NZ-86-m produced hydrogen at comparable rates to Anabaena cylindrica. The conversion efficiency of light to hydrogen energy at maximum rates of hydrogen production was 2.7%.     

The evolution of dinitrogen fixation

It is argued that nitrogenase originated monophyletically in obligate anaerobes similar to Clostridia. The enzyme system was later inherited, without much change, by photosynthetic bacteria, by prokaryotic plants (blue-greens) and by aerobic bacteria. The hydrogenase function of the enzyme complex preceded the nitrogenase function, and was useful in hydrogen fermentations. The consumption of ATP served to assure disposal of electrons in the form of hydrogen gas. The present need of the enzyme system, whether acting as a hydrogenase or as a nitrogenase, for ATP may be a relic from the period when the biosphere was still reducing.