甲烷氧化菌利用甲烷生产聚羟基脂肪酸的研究进展

化学合成塑料主要来自于不可再生的化石能源,化学合成塑料的大量使用既消耗了大量能源物质,也带来了严重的环境问题。而生物合成的高分子化合物聚羟基脂肪酸,具有与合成塑料相似的物理性质,生产原料具有可再生性,同时在环境能快速降解,结构多样可以满足不同用途等多种优点,成为合成塑料最佳的替代品。甲烷氧化菌能以甲烷为唯一碳源和能源物质生长,并在细胞内合成大分子聚羟基脂肪酸。利用甲烷氧化菌转化甲烷合成聚羟基脂肪酸不仅可以大幅降低生产成本,同时也减少了温室气体的排放。本文就甲烷氧化菌合成聚羟基脂肪酸的生物代谢途径,甲烷为原料生产聚羟基脂肪酸的方法及优缺点等方面进行了分析。     

颗粒性甲烷单加氧酶分离纯化方法的研究进展

颗粒性甲烷单加氧酶(pMMO)是甲烷氧化菌的特征酶之一,在生物催化方面具有广泛的应用前景,但由于其内膜蛋白的性质以及纯化过程中的不稳定性,使其生物化学性质、金属活性位点等方面仍存在许多未知和争议.着重总结了颗粒性甲烷单加氧酶的分离纯化方法,并对其活性以及与甲烷氧化菌素-Cu(methanobactin-Cu)和其他物质之间的作用关系进行了概述,以促进颗粒性甲烷单加氧酶的深入研究和应用.     

生物柴油及1,3-丙二醇联产工艺产业化进展

生物柴油作为可再生的清洁能源,已在美国、欧盟等多个国家和地区推行使用.在生物柴油的生产过程中,最高可得到约10%的副产物甘油,副产物甘油的去向将成为生物柴油大规模产业化发展所面临的严峻问题.1,3-丙二醇是一种重要的化工原料,作为合成新型聚酯PTT的原料,1,3-丙二醇已引起人们的广泛关注.以生物柴油副产物甘油为原料耦合生产1,3-丙二醇,不仅解决了生物柴油副产物甘油的出路问题,同时降低了1,3-丙二醇的生产成本.本文详细介绍了生物柴油及1,3-丙二醇生产技术及联产工艺的研究进展,并对其应用前景进行了展望.     

生物柴油及1,3-丙二醇联产工艺产业化进展

生物柴油作为可再生的清洁能源,已在美国、欧盟等多个国家和地区推行使用.在生物柴油的生产过程中,最高可得到约10%的副产物甘油,副产物甘油的去向将成为生物柴油大规模产业化发展所面临的严峻问题.1,3-丙二醇是一种重要的化工原料,作为合成新型聚酯PTT的原料,1,3-丙二醇已引起人们的广泛关注.以生物柴油副产物甘油为原料耦合生产1,3-丙二醇,不仅解决了生物柴油副产物甘油的出路问题,同时降低了1,3-丙二醇的生产成本.本文详细介绍了生物柴油及1,3-丙二醇生产技术及联产工艺的研究进展,并对其应用前景进行了展望.     

细胞工厂与生物炼制

生物炼制是以可再生生物质资源为原料,生产能源与化工产品的新兴工业模式.是转变经济增长模式,保障社会经济可持续发展的重大战略需求.微生物细胞工厂是生物炼制技术至关重要的核心.世界各国纷纷设立重大研究计划支持细胞工厂的研究,以期获得生物炼制技术的领先地位.本文简要概括了细胞工厂和生物炼制这一新兴工业模式,回顾了生物炼制细胞工厂的重大计划和进展,讨论了目前亟待解决的关键问题和研究对策.     

细胞工厂与生物炼制

生物炼制是以可再生生物质资源为原料,生产能源与化工产品的新兴工业模式.是转变经济增长模式,保障社会经济可持续发展的重大战略需求.微生物细胞工厂是生物炼制技术至关重要的核心.世界各国纷纷设立重大研究计划支持细胞工厂的研究,以期获得生物炼制技术的领先地位.本文简要概括了细胞工厂和生物炼制这一新兴工业模式,回顾了生物炼制细胞工厂的重大计划和进展,讨论了目前亟待解决的关键问题和研究对策.     

微藻的高油脂化技术

温室效应与石化能源紧缺已成为全球问题,生物燃料作为一种可再生且环境友好的替代能源受到人们的普遍关注。不少微藻油含量高,环境适应性强,净碳值几乎为零,被认为是生物质能,尤其生物柴油最重要的原料来源之一。本文综述了油脂微藻的国内外研究现状,并对高油脂微藻藻种筛选、高密度培养,以及提高微藻油脂含量和产油速率的可能方法进行了讨论;阐述了采用基因工程技术调控微藻脂类代谢途径生产高油脂的可能性;最后介绍了以CO2废气为碳源,膜生物反应器强化微藻培养技术,为进一步降低微藻产油成本,提高微藻生物柴油经济性提出了一条极有可能实现工业化的潜在高效生产途径。     

微藻的高油脂化技术研究进展

温室效应与石化能源紧缺已成为全球问题,生物燃料作为一种可再生且环境友好的替代能源受到人们的普遍关注。不少微藻油含量高,环境适应性强,净碳值几乎为零,被认为是生物质能,尤其是生物柴油最重要的原料来源之一。本文综述了油脂微藻的国内外研究现状,并对高油脂微藻藻种筛选、高密度培养,以及提高微藻油脂含量和产油速率的可能方法进行了讨论;阐述了采用基因工程技术调控微藻脂类代谢途径生产高油脂的可能性;最后介绍了以CO2废气为碳源,膜生物反应器强化微藻培养技术,为进一步降低微藻产油成本,提高微藻生物柴油经济性提出了一条极有可能实现工业化的潜在高效生产途径。     

机械合金化制备金属间化合物SbSn及其在原油乳液脱硫中的应用

原油中有机硫化物的增多和重质化[1]在炼制过程中易造成设备腐蚀,同时部分硫氧化生成的SO2排放至大气中,可产生酸雨,对环境造成污染.世界各国对成品油中硫含量的规定日益严格,尤其是在各国燃料结构中占有较高份额的汽油、煤油和柴油.     

温和条件下催化甲烷氧化制甲醇研究进展

甲烷是燃料或化工生产中最丰富的碳基能源之一,将甲烷转化为液体或固体化学原料将成为全球能源供应的转折点.目前,许多催化此类反应的工作已有大量研究和报道.在这些反应中,甲烷选择性氧化制甲醇被认为是天然气就地价值化的一条有前途的途径.这使得甲烷低温选择性氧化制甲醇技术的发展变得非常迫切,本文综述了CH₄的活化和催化转化,指出了针对特定反应的催化剂的发展趋势.讨论了理想条件下甲烷氧化制取甲烷的反应研究以及Au–Pd合金类、ZSM-5类、MOFs类、单原子类等催化剂对甲烷氧化过程的影响及其催化转化机理.最后,对温和条件下催化甲烷氧化制甲醇催化剂未来发展提出了展望和挑战.     

生物柴油的发展概况与应用前景

石化燃料是当前人类使用的主要能源,但其使用造成了严重的温室效应和环境污染．生物柴油具有安全、无污染、燃烧好、可再生等优点而被当作石化燃料的绿色替代品．本文阐述了生物柴油的本质及其相对于石化柴油在使用上的优良特性,综述了国内外生物柴油技术的研究、应用及产业发展概况,论述了生物柴油研究的重要意义．根据菜油的特点及油菜在我国的发展前景,认为油菜可能是我国发展生物柴油的理想原料．     

Valorization of Food and Agricultural Waste: A Step towards Greener Future

With the progress in technology and population, an enormous amount of agricultural and food waste is being generated throughout the world. In the past, food and agro‐wastes were either burnt off or allowed to rot in fields, but this can be potentially hazardous to the environment. Therefore, approaches with respect to their utilization, reuse, and processing need to be developed to enable the sustainable utilization of feedstock and reduce pollution. Agricultural wastes mainly comprise of cellulosic fibres possessing high fixed carbon content and multifunctional groups. Agricultural waste shows considerable applicability due to its high strength, environmentally benign nature, low cost, and ease of availability and reusability. All these characteristics have been researched upon in the past, in the sector of waste water management for the removal of heavy metals and dyes. Similarly, a variety of food and agro‐waste has been adopted as sources for new drug leads or important phytochemicals with different therapeutic benefits. Agro‐waste can also be employed for enzyme immobilization after proper modification. Apart from this waste cooking oil comes under the category of food waste and can be processed to prepare alternate energy source such as biodiesel. This personal account summarizes the development, processing, and application of food and agro‐waste in the production of biodiesel, environmental remediation, curative medicine, and in the development of biocatalysts, by researchers in our laboratory.     

Supercritical synthesis of biodiesel

The synthesis of biodiesel fuel from lipids (vegetable oils and animal fats) has gained in importance as a possible source of renewable non-fossil energy in an attempt to reduce our dependence on petroleum-based fuels. The catalytic processes commonly used for the production of biodiesel fuel present a series of limitations and drawbacks, among them the high energy consumption required for complex purification operations and undesirable side reactions. Supercritical fluid (SCF) technologies offer an interesting alternative to conventional processes for preparing biodiesel. This review highlights the advances, advantages, drawbacks and new tendencies involved in the use of supercritical fluids (SCFs) for biodiesel synthesis.     

Medium-Chain Fatty Acids (MCFA) Production Through Anaerobic Fermentation Using <Emphasis Type="Italic">Clostridium kluyveri</Emphasis>: Effect of Ethanol and Acetate

Medium-chain fatty acids (MCFA) are saturated monocarboxylic acids and can be used as antimicrobials, corrosion inhibitors, precursors in biodiesel, and bioplastic production. In the present study, MCFA production was evaluated with acetate and ethanol using the bacteria Clostridium kluyveri. Effects of substrate, electron donor, and methane inhibitor on MCFA production were evaluated. Bacteria successfully converted the ethanol and acetate to butyrate (C4), caproate (C6), and caprylate (C8) by chain elongation process. The highest concentrations of butyrate (4.6 g/l), caproate (3.2 g/l), and caprylate (0.5 g/l) were obtained under methane inhibition conditions than other conditions. The productions of butyrate and caproate were 1.6 and 1.48 times higher under methane inhibition conditions, respectively. Results denoted that the bacteria C. kluyveri can be used for conversion of acetate and ethanol into useful products like butyrate and caproate.     

Emission profile of rapeseed methyl ester and its blend in a diesel engine

Fatty acid methyl esters, also known as biodiesel, have been shown to have a great deal of potential as petro-diesel substitutes. Biodiesel comprise a renewable alternative energy source, the development of which would clearly reduce global dependence on petroleum and would also help to reduce air pollution. This paper analyzes the fuel properties of rapeseed biodiesel and its blend with petro-diesel, as well as the emission profiles of a diesel engine on these fuels. Fuels performance studies were conducted in order to acquire comparative data regarding specific fuel consumption and exhaust emissions, including levels of carbon monoxide (CO), carbon dioxide (CO₂), smoke density, and NO_x, in an effort to assess the performance of these biodiesel and blend. The fuel consumption amount of oil operations at high loads was similar or greater than that observed during petro-diesel operation. The use of biodiesel is associated with lower smoke density than would be seen with petro-diesel. However, biodiesel and its blend increased the emission of CO, CO₂, and nitrogen oxides, to a greater degree than was seen with petro-diesel. The above results indicate that rapeseed biodiesel can be partially substituted for petro-diesel under most operating conditions, regarding both performance parameters and exhaust, without any modifications having to be made to the engine.     

Biological Hydrogen Production Using Chloroform-treated Methanogenic Granules

In fermentative hydrogen production, the low-hydrogen-producing bacteria retention rate limits the suspended growth reactor productivity because of the long hydraulic retention time (HRT) required to maintain adequate bacteria population. Traditional bacteria immobilization methods such as calcium alginate entrapment have many application limitations in hydrogen fermentation, including limited duration time, bacteria leakage, cost, and so on. The use of chloroform-treated anaerobic granular sludge as immobilized hydrogen-producing bacteria in an immobilized hydrogen culture may be able to overcome the limitations of traditional immobilization methods. This paper reports the findings on the performance of fed-batch cultures and continuous cultures inoculated with chloroform-treated granules. The chloroform-treated granules were able to be reused over four fed-batch cultures, with pH adjustment. The upflow reactor packed with chloroform-treated granules was studied, and the HRT of the upflow reactor was found to be as low as 4 h without any decrease in hydrogen production yield. Initial pH and glucose concentration of the culture medium significantly influenced the performance of the reactor. The optimum initial pH of the culture medium was neutral, and the optimum glucose concentration of the culture medium was below 20 g chemical oxygen demand/L at HRT 4 h. This study also investigated the possibility of integrating immobilized hydrogen fermentation using chloroform-treated granules with immobilized methane production using untreated granular sludge. The results showed that the integrated batch cultures produced 1.01 mol hydrogen and 2 mol methane per mol glucose. Treating the methanogenic granules with chloroform and then using the treated granules as immobilized hydrogen-producing sludge demonstrated advantages over other immobilization methods because the treated granules provide hydrogen-producing bacteria with a protective niche, a long duration of an active culture, and excellent settling velocity. This integrated two-stage design for immobilized hydrogen fermentation and methane production offers a promising approach for modifying current anaerobic wastewater treatment processes to harvest hydrogen from the existing systems.     

Dioxygen Activation and Methane Hydroxylation by Soluble Methane Monooxygenase: A Tale of Two Irons and Three Proteins A list of abbreviations can be found in Section 7

Methanotrophic bacteria are capable of using methane as their sole source of carbon and energy. The first step in methane metabolism, the oxidation of methane to methanol, is catalyzed by a fascinating enzyme system called methane monooxygenase (MMO). The selective oxidation of the very stable C-H bond in methane under ambient conditions is a remarkable feat that has not yet been repeated by synthetic catalysts and has attracted considerable scientific and commercial interest. The best studied MMO is a complex enzyme system that consists of three soluble protein components, all of which are required for efficient catalysis. Dioxygen activation and subsequent methane hydroxylation are catalyzed by a hydroxylase enzyme that contains a non-heme diiron site. A reductase protein accepts electrons from NADH and transfers them to the hydroxylase where they are used for the reductive activation of O(2). The third protein component couples electron and dioxygen consumption with methane oxidation. In this review we examine different aspects of catalysis by the MMO proteins, including the mechanisms of dioxygen activation at the diiron site and substrate hydroxylation by the activated oxygen species. We also discuss the role of complex formation between the different protein components in regulating various aspects of catalysis.     

生物柴油及1,3-丙二醇联产工艺产业化进展

生物柴油作为可再生的清洁能源,已在美国、欧盟等多个国家和地区推行使用。在生物柴油的生产过程中,最高可得到约10%的副产物甘油,副产物甘油的去向将成为生物柴油大规模产业化发展所面临的严峻问题。1,3-丙二醇是一种重要的化工原料,作为合成新型聚酯PTT的原料,1,3-丙二醇已引起人们的广泛关注。以生物柴油副产物甘油为原料耦合生产1,3-丙二醇,不仅解决了生物柴油副产物甘油的出路问题,同时降低了1,3-丙二醇的生产成本。本文详细介绍了生物柴油及1,3-丙二醇生产技术及联产工艺的研究进展,并对其应用前景进行了展望。     

Biosynthesis of methanol from methane by <Emphasis Type="Italic">Methylosinus trichosporium</Emphasis> OB3b

Methanol has recently attracted significant interest in the energetic field. Current technology for the conversion of methane to methanol is based on energy intensive endothermic steam reforming followed by catalytic conversion into methanol. The one-step method performed at very low temperatures (35°C) is methane oxidation to methanol via bacteria. The aim of this work was to examine the role of copper in the one-step methane oxidation to methanol by utilizing whole cells of Methylosinus trichosporium OB3b bacteria. From the results obtained it was found that copper concentration in the medium influences the rate of bacterial biomass growth or methanol production during the process of methane oxidation to methanol. The presented results indicate that the process of methane oxidation to methanol by Methylosinus trichosporium OB3b bacteria is most efficient when the mineral medium contains 1.0 × 10⁻⁶ mol dm⁻³ of copper. Under these conditions, a satisfactory growth of biomass was also achieved. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

Growth of Chlorella vulgaris on Sugarcane Vinasse: The Effect of Anaerobic Digestion Pretreatment

Microalgae farming has been identified as the most eco-sustainable solution for producing biodiesel. However, the operation of full-scale plants is still limited by costs and the utilization of industrial and/or domestic wastes can significantly improve economic profits. Several waste effluents are valuable sources of nutrients for the cultivation of microalgae. Ethanol production from sugarcane, for instance, generates significant amounts of organically rich effluent, the vinasse. After anaerobic digestion treatment, nutrient remaining in such an effluent can be used to grow microalgae. This research aimed to testing the potential of the anaerobic treated vinasse as an alternative source of nutrients for culturing microalgae with the goal of supplying the biodiesel industrial chain with algal biomass and oil. The anaerobic process treating vinasse reached a steady state at about 17 batch cycles of 24 h producing about 0.116 m³CH₄ kgCOD_vinasse ^?1. The highest productivity of Chlorella vulgaris biomass (70 mg l^?1 day^?1) was observed when using medium prepared with the anaerobic digester effluent. Lipid productivity varied from 0.5 to 17 mg l^?1 day^?1. Thus, the results show that it is possible to integrate the culturing of microalgae with the sugarcane industry by means of anaerobic digestion of the vinasse. There is also the advantageous possibility of using by-products of the anaerobic digestion such as methane and CO₂ for sustaining the system with energy and carbon source, respectively.