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1.
利用光能驱动二氧化碳(carbon dioxide, CO2)还原生产化学品对于缓解环境压力、解决能源危机具有重要意义。光捕获、光电转化和CO2固定等作为影响光合作用效率的关键因素,同时也制约着CO2的资源化利用效率。为了解决上述问题,本文从生物化学与代谢工程相结合的角度,系统总结了光驱动杂合系统的构建、优化与应用,并从酶杂合系统、生物杂合系统以及杂合系统应用3个方面分析了光驱动CO2还原合成化学品的最新研究进展。在酶杂合系统方面,采用的策略主要有提升酶催化活性、增强酶稳定性等;在生物杂合系统方面,采用的方法主要包括增强生物捕光能力、优化还原力供应以及改善能量再生等;在杂合系统应用方面,主要阐述了光驱动CO2还原生产一碳含能化合物、生物燃料以及生物食品等。最后,从纳米材料(包括有机材料和无机材料)和生物催化剂(包括酶和微生物)两个方面,展望了人工光合系统的进一步发展方向。  相似文献   

2.
微藻固定CO2研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
空气中CO2 浓度升高所导致的温室效应已成为重大的环境问题 ,受到人们普遍关注。概述了高效固定CO2 微藻藻种的筛选和培养方法 ,分析了微藻固定CO2 的无机碳利用形式和浓缩机制 ,讨论了高效光生物反应器设计和运行目标 ,简要介绍了微藻 (酶 ) 膜生物反应器集成新技术。并认为今后的研究方向主要是在进一步探索微藻固定CO2 有关机理的基础上 ,构建高效固定CO2 的转基因微藻 ,开发高效膜生物反应集成系统。  相似文献   

3.
有机相酶促酯化反应中水分调控技术的研究   总被引:2,自引:0,他引:2  
在有机相酶促反应中,水含量是影响酶活力的关键因素.对异辛烷/正辛醇体系中柱状假丝酵母脂肪酶催化萘普森酯化反应中的水分调控技术进行了研究. 结果表明:水合盐对——Na2SO4·10H2O/Na2SO4对系统水分的变化具有有效的缓冲作用;非极性硅藻土吸附固定酶,使之对水分的敏感性得到缓解;另外,加入分子筛去除副产物——“水”可促进酯化过程的进行.  相似文献   

4.
张彪  谢紫霞  高吉喜 《生态学报》2021,41(22):8906-8920
植被固碳功能是城市森林的重要生态服务之一,但是定量揭示城市森林植被固碳功能空间格局及其抵消碳排放的研究较少。基于光合速率法和生物量法测算了上海城市森林植被的固定CO2功能,并结合其空间分布格局与区域CO2排放状况对比分析了抵消能源CO2排放的成效。结果表明,2017年上海城市森林植被可固定CO2 135.57万t,约合单位面积固碳17.02 t/hm2。上海城市森林植被的固定CO2功能呈现出"中间低、四周高"的空间格局,崇明区和浦东新区的城市森林植被提供了近52.8%的固定CO2效益。2017年上海市能源消费的CO2排放量高达2.73亿t,且呈现出"中间高、四周低"空间分布特征,中心城区能源CO2排放约占11.49%。整体来看,上海城市森林植被可抵消0.50%的能源CO2排放,但植被固定CO2功能与能源CO2排放的空间匹配较差,中心城区城市森林植被的CO2抵消率仅为0.08%。因此,重点提升中心城区森林植被的固碳功能并加强海洋碳吸收功能的监测与利用尤其重要。  相似文献   

5.
鸟氨酸脱羧酶活性微量测定法   总被引:1,自引:0,他引:1  
本文采用一种简单,微量反应系统,根据 14C-鸟氨酸释放的 14CO2量测定鸟氨酸脱羧酶(ODC)的活性,酶反应在置于液闪计数瓶内的玻璃小管中进行,释放的 14CO2被瓶内滤纸片上的海胺吸收。实验结果表明,加酸释放 14CO2后30分钟 14CO2吸收已达最大值,且吸收量与释放量成正比,酶反应测定证明 14CO2释放速度在40分钟内保持恒定。ODC活性与酶浓度呈线性关系,此方法不仅用于ODC活性测定,而且亦可用于其他脱羧酶活性的测定。  相似文献   

6.
过氧化氢酶(catalase,CAT)是一种在食品、医疗、纺织等领域广泛应用的工业酶,具有催化效率高、专一性强、绿色环保等突出特点。工业中游离过氧化氢酶无法回收再利用,导致以其为核心的工业生物转化过程成本较高。开发一种简单、温和、低成本并且体现绿色化学理念的方法对过氧化氢酶进行固定化有望提高其利用率并且强化酶学性能,具有迫切的现实需求。本研究将源自枯草芽孢杆菌(Bacillus subtilis)168的过氧化氢酶KatA在大肠杆菌中进行重组表达,之后将分离纯化得到的纯酶以酶-无机杂化纳米花形式制备成固定化酶并进行酶学性质研究。结果显示,利用乙醇沉淀、DEAE阴离子交换层析、疏水层析3步纯化,最终获得电泳纯的重组KatA,之后通过优化制备条件获得了一种新型KatA/Ca3(PO4)2杂化纳米花固定化酶。酶学性质研究结果显示,游离酶KatA的最适反应温度为35℃,KatA/Ca3(PO4)2杂化纳米花的最适反应温度为30−35℃,二者最适反应pH值均为11.0。游离酶KatA和KatA/Ca3(PO4)2杂化纳米花在pH4.0−11.0和25−50℃条件下均表现出较好的稳定性。KatA/Ca3(PO4)2杂化纳米花显示出比游离酶KatA更好的储存稳定性,在4℃储存14d后仍保留82%的酶活力,而游离酶仅具有50%的酶活力。此外,纳米花在进行5次催化反应后仍具有55%的酶活力,表明其具有较好的操作稳定性。动力学研究结果显示,游离酶KatA对底物过氧化氢的Km为(8.80±0.42)mmol/L,kcat/Km为(13151.53±299.19)L/(mmol·s);而KatA/Ca3(PO4)2杂化纳米花的Km为(32.75±2.96)mmol/L,kcat/Km为(4550.67±107.51)L/(mmol·s)。与游离酶KatA相比,KatA/Ca3(PO4)2杂化纳米花对底物过氧化氢的亲和力下降,同时其催化效率也有所降低。综上所述,本研究以Ca2+作为自组装诱导剂,成功将KatA以酶-无机杂化纳米花形式制备成固定化酶,不仅对部分酶学性能实现了强化,而且为固定化过氧化氢酶的绿色制备和规模化应用奠定了基础。  相似文献   

7.
应用FIA型微生物传感器测定谷氨酸含量的研究   总被引:1,自引:0,他引:1  
目前应用酶或微生物细胞作为分子识别元件构建生物传感器测定谷氨酸含量的研究引起了广泛的兴趣,并陆续有实例报道。在这些报道中人们依据不同的酶催反应选择相应的离子选择性电极,如CO2电极、NH4+电极等,而测量对象有直接的测定谷氨酸,也有测定谷氨酸单钠的间接测定法。本文选用了可固定大量细胞的固定化细胞柱与流动注入法相结合的测量方法,并根据细胞柱的动力学模型分析动态响应曲线,计算测量结果,提高了测量精度,扩大了测量范围。  相似文献   

8.
余珂  张尹  吕雪艳  于志国 《生态学报》2021,41(24):9705-9716
硫、铁是泥炭沼泽湿地(泥炭地)中重要的生源要素,其参与下的生物地球化学过程对泥炭地碳循环意义重大。选取德国中部两处典型的雨养型泥炭地高海拔样点(TBP)和低海拔样点(TSP),通过原位采集泥炭剖面孔隙水和可溶性气体等,研究了硫、铁元素等地球化学变化规律,结合DOC、甲烷(CH4)和二氧化碳(CO2)浓度分布,探讨其对泥炭地碳排放的影响。研究结果表明:(1) TBP中总还原无机硫(TRIS)浓度随深度先增后减,且上部0-87 cm平均浓度远高于87 cm深度以下,上部硫酸盐还原作用强烈。结合上部亚铁、硫化氢(H2S)浓度分布,得知该范围内H2S主要是通过微生物硫酸盐还原作用(BSR)生成,同时H2S在孔隙水扩散过程中易与亚铁结合为硫化亚铁,进而生成稳定的黄铁矿,这一反应过程在约60 cm处减缓。(2) TBP、TSP两处采样点中DOC与亚铁、硫酸盐均有较强相关性,是由于地下水位的波动影响氧化还原程度以及微生物活性。两处采样点DOC均与亚铁呈显著正相关关系,表明铁氧化物在厌氧环境中被还原溶解产生亚铁,与其结合的有机碳被释放到溶液中从而导致DOC浓度的升高。TBP中DOC与硫酸盐呈显著负相关关系,表明硫酸盐作为电子受体被还原的过程中消耗酸度使pH值升高,增强了其中微生物的活性,DOC浓度由此增加。(3) CH4与硫酸盐、TRIS浓度在剖面上均呈现相反变化趋势,表明硫酸盐输入的增加以及硫酸盐还原活动均会抑制CH4生成。CO2/CH4均大于4,表明硫酸盐作为替代电子受体会使厌氧条件下碳矿化转向多CO2和少CH4生成。此外,亚铁对于CH4生成一定程度上会起到低促高抑的效果,而对于CO2的生成的影响较弱。表明硫酸盐对于CH4和CO2生成的影响高于亚铁。研究着重探究硫、铁等关键元素地下部生物地球化学过程对碳排放的影响机制,研究结果可为泥炭地碳排放核算提供理论支撑。  相似文献   

9.
多孔醋酸纤维素球形载体固定化糖化酶的研究   总被引:11,自引:1,他引:10  
报道了一种多孔醋酸纤维素球形固定化酶载体的制备技术,以NaIO4氧化法活化,固定糖化酶,测定了固定化糖化酶的催化反应特性,并与游离酶作了比较.固定化酶在55℃下水解10批淀粉溶液,总反应时间超过24 h,活力无显著变化.  相似文献   

10.
王学霞  王国红  戈峰 《生态学报》2011,31(3):629-637
以CO2浓度升高为作用因子,观测了连续3代饲养在转Bt基因棉(GK-12)和亲本棉泗棉3号(S3)上B型烟粉虱的个体大小、解毒酶活性及第3代烟粉虱的选择性和产卵量。结果表明,CO2浓度和棉花品种处理对第2、3代烟粉虱卵长、伪蛹大小、雌雄成虫大小的影响均不显著,但CO2浓度升高使第1代烟粉虱的伪蛹长、雌虫翅展和雌、雄虫长显著低于对照CO2浓度下生长的烟粉虱;取食S3的伪蛹长、雌虫长和雌虫翅展分别比相应的对照浓度下的低2.81%、2.95%、0.94%,取食GK-12的雌虫翅展和雄虫长均比相应的对照浓度下的低2.08%和2.58%。3种解毒酶的活性测定显示,取食高CO2浓度处理的转基因棉GK-12上的F3代烟粉虱的谷胱甘肽S转移酶(Glutathione Stransferase, 简称GSTs)活性和取食亲本棉S3的F1代的乙酰胆碱酯酶(Acetylcholinesterase;简称AchE)的活性分别比对照处理的增加45.73%和27.68%;而羧酸酯酶(Carboxylic Ester hydrolase;简称 CarE)在取食4个处理的棉花上烟粉虱的活性均无显著的差异;而取食对照CO2条件下GK-12棉花的F1代烟粉虱GSTs活性比取食S3棉花低35.12%。对3个因子的交互分析结果显示,C02浓度对3种酶活影响均不显著,品种对GSTs的影响显著,世代、CO2×品种及CO2×品种×世代间的交互作用对AchE酶活影响显著,各因子对CarE的活性影响均不显著。烟粉虱的选择实验结果表明,4种处理的F3代B型烟粉虱均喜好选择在高CO2处理的棉花,而且选择高CO2处理的GK-12的数量多于其他3个处理,其中对照浓度下生长的烟粉虱选择高CO2的GK-12比高CO2处理的S3、对照浓度处理的GK-12 和S3分别增加9.175%, 19.89%、27.93%; 而高浓度下生长的烟粉虱选择高CO2的GK-12比高CO2处理的S3、对照浓度处理的GK-12 和S3分别增加12.56%,21.05%,28.73%。72h的产卵量检测发现,烟粉虱在高CO2处理的2种棉花上的产卵量也是多于对照条件下的棉花,对照条件下的棉花相比,高CO2和对照浓度下生长的烟粉虱的在高CO2处理的2种棉花上的产卵量分别增加24.55%和19.03%;在高CO2浓度下生长的F3代烟粉虱更喜好在高CO2浓度处理的GK-12上产卵,与对照浓度下的GK-12相比增加26.93%,差异达到显著水平。  相似文献   

11.
The global atmospheric CO2 concentration reached 147% of pre‐industrial levels in 2019, and is still increasing with an accelerated rate. A series of methods have been developed to convert CO2 to other non‐greenhouse molecules. Elelctrocatalytic CO2 reduction reaction (CO2RR) is one of the promising methods, since it could support renewable energy. Optimizing the CO2RR system requires finding highly efficient catalysts, as well as electrolysis systems. In this essay, the development of promising heterogeneous catalysts with well‐defined active metal sites is discussed. These catalysts could be prepared by immobilizing metal cations onto chemically well‐defined substrates, such as metal‐organic frameworks, covalent‐organic frameworks, polyoxometalates, or immobilizing well‐defined molecular catalysts on conducting substrates. A clear perspective on the catalyst's structures contributes to the understanding of structure‐reactivity correlations, which could, in turn, shed light on designing better catalysts. Some methods to assist the electrocatalysis process, such as coupling with solar or heat energy, are also briefly discussed.  相似文献   

12.
Electrochemical reduction of carbon dioxide (CO2) typically suffers from low selectivity and poor reaction rates that necessitate high overpotentials, which impede its possible application for CO2 capture, sequestration, or carbon‐based fuel production. New strategies to address these issues include the utilization of photoexcited charge carriers to overcome activation barriers for reactions that produce desirable products. This study demonstrates surface‐plasmon‐enhanced photoelectrochemical reduction of CO2 and nitrate (NO3?) on silver nanostructured electrodes. The observed photocurrent likely originates from a resonant charge transfer between the photogenerated plasmonic hot electrons and the lowest unoccupied molecular orbital (MO) acceptor energy levels of adsorbed CO2, NO3?, or their reductive intermediates. The observed differences in the resonant effects at the Ag electrode with respect to electrode potential and photon energy for CO2 versus NO3? reduction suggest that plasmonic hot‐carriers interact selectively with specific MO acceptor energy levels of adsorbed surface species such as CO2, NO3?, or their reductive intermediates. This unique plasmon‐assisted charge generation and transfer mechanism can be used to increase yield, efficiency, and selectivity of various photoelectrochemical processes.  相似文献   

13.
The kinetics of 1-ethyl-3-(3′-dimethylaminopropyl)-carbodiimide interaction with carboxylic groups in low and high molecular weight compounds have been investigated for choosing the optimum conditions for enzyme immobilization on carboxylic carriers. Optimum pH values depended on the pKa of an acid. The ionic strength of the reaction mixture influenced the process of activation with carbodiimide and a decrease in reaction rate accompanied an increase in ionic strength. Optimum conditions for the coupling process with the use of carbodiimide activation are suggested. The process of fibrinolysin immobilization on the soluble copolymer of acrylic acid and acrylamide with carbodiimide as a coupling agent was also studied.  相似文献   

14.
Formate dehydrogenase from Candida boidinii (CbFDH) is potentially applicable in reduction of CO2 through oxidation of cofactor NADH into NAD+. For this, the CbFDH activity needs to be maintained under practical reaction conditions, such as CO2 gas‐liquid flow. In this work, CbFDH and cofactor were encapsulated in liposomes and the liposomal enzymes were characterized in an external loop airlift bubble column. The airlift was operated at 45°C with N2 or CO2 as gas phase at the superficial gas velocity UG of 2.0 or 3.0 cm/s. The activities of liposomal CbFDH/cofactor systems were highly stable in the airlift regardless of the type of gas phase because liposome membranes prevented interactions of the encapsulated enzyme and cofactor molecules with the gas‐liquid interface of bubbles. On the other hand, free CbFDH was deactivated in the airlift especially at high UG with CO2 bubbles. The liposomal CbFDH/NADH could catalyze reduction of CO2 in the airlift giving the fractional oxidation of the liposomal NADH of 23% at the reaction time of 360 min. The cofactor was kept inside liposomes during the reaction operation with less than 10% of leakage. All of the results obtained demonstrate that the liposomal CbFDH/NADH functions as a stable catalyst for reduction of CO2 in the airlift. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010  相似文献   

15.
In the global transition to a sustainable low‐carbon economy, CO2 capture and storage technology still plays a critical role for deep emission reduction, particularly for the stationary sources in power generation and industry. However, for small and mobile emission sources in transportation, CO2 capture is not suitable and it is more practical to use relatively clean energy, such as natural gas. In these two low‐carbon energy technologies, designing highly selective sorbents is one of the key and most challenging steps. Toward this end, metal‐organic frameworks (MOFs) have received continuously intensive attention in the past decades for their highly porous and diversified structures. In this review, the recent progress in developing MOFs for selective CO2 capture from post‐combustion flue gas and CH4 storage for vehicle applications are summarized. For CO2 capture, several promising strategies being used to improve CO2 adsorption uptake at low pressures are highlighted and compared. In addition, the conventional and novel regeneration techniques for MOFs are also discussed. In the case of CH4 storage, the flexible and rigid MOFs, whose CH4 storage capacity is close to the target set by U.S. Department of Energy are particularly emphasized. Finally, the challenge of using MOFs for CH4 storage is discussed.  相似文献   

16.
These studies demonstrated that CO2 rather than HCO3 is the inorganic carbon metabolite produced by the C4 acid decarboxylases involved in C4 photosynthesis (chloroplast located NADP malic enzyme, mitochondrial NAD malic enzyme, and cytosolic phosphoenolpyruvate [PEP] carboxykinase). The effect of varying CO2 or HCO3 as a substrate for the carboxylation reaction catalyzed by these enzymes or as inhibitors of the decarboxylation reaction was also determined. The KmCO2 was 1.1 millimolar for NADP malic enzyme and 2.5 millimolar for PEP carboxykinase. For these two enzymes the velocity in the carboxylating direction was substantially less than for the decarboxylating direction even with CO2 concentrations at the upper end of the range of expected cellular levels. Activity of NAD malic enzyme in the carboxylating direction was undetectable. The decarboxylation reaction of all three enzymes was inhibited by added HCO3. For NADP malic enzyme CO2 was shown to be the inhibitory species but PEP carboxykinase and NAD malic enzyme were apparently inhibited about equally by CO2 and HCO3.  相似文献   

17.
Three β-d-galactosidases (β-d-galactoside galactohydrolase, EC 3.2.1.23) from different origins have been immobilized on sucrose-polyacrolein and sucrose sulphate-polyacrolein. This gave enzyme conjugates insoluble in the immobilization medium but which could be made soluble by reduction with sodium borohydride before use. The optimum conditions for both copolymer synthesis and the immobilization reaction were investigated. I.r. and 13C n.m.r. spectroscopy were used to follow the sulphation and the copolymerization reaction. The characteristics of the enzyme conjugates were compared with those of the free enzymes: the Vmax values of the enzyme conjugates were lower than those of the corresponding free enzymes, whilst the Km values were similar. The thermal stability of the enzyme conjugates depended on the enzyme origin, while their pH stability was in all cases higher than that of the free enzymes. These data suggest some advantages in using enzyme immobilization supports which can be made soluble after separation of the immobilized enzyme without altering the enzyme characteristics.  相似文献   

18.
The CO2-concentrating mechanism (CCM) in cyanobacteria supports high rates of photosynthesis by greatly increasing the concentration of CO2 around the major carbon fixing enzyme, Rubisco. However, the CCM remains poorly understood, especially in regards to the enigmatic CO2-hydration enzymes which couple photosynthetically generated redox energy to the hydration of CO2 to bicarbonate. This CO2-hydration reaction is catalysed by specialized forms of NDH-1 thylakoid membrane complexes that contain phylogenetically unique extrinsic proteins that appear to couple CO2 hydration to NDH-1 proton pumping. The development of the first molecular genetic system to probe structure-function relationships of this important enzyme system is described. A CO2-hydration deficient strain was constructed as a recipient for DNA constructs containing different forms of the CO2-hydration system. This was tested by introducing a construct to an ectopic location that gives constitutive expression, rather than native inducible expression, of the ndhF3-ndhD3-cupA-cupS, (cupA operon) encoding high affinity CO2-hydration complex, NDH-13. Uptake assays show the restoration of high affinity for CO2 uptake, but demonstrate that the CupA complex can drive only modest uptake fluxes, underlining the importance of its tandem operation with the CupB-containing complex NDH-14, the complementary high flux, low affinity CO2 hydration system. Experiments with the carbonic anhydrase inhibitor, ethoxyzolamide, indicate that the NDH-13 complex is strongly inhibited, yet the remaining NDH-14 activity in the wild-type is less so, suggesting structural differences between the low affinity and high affinity CO2–hydration systems. This new construct will be an important tool to study and better understand cyanobacterial CO2 uptake systems.  相似文献   

19.
NAD-dependent formate dehydrogenase (FDH) from Candida boidinii (CbFDH) has been widely used in various CO2-reduction systems but its practical applications are often impeded due to low CO2-reducing activity. In this study, we demonstrated superior CO2-reducing properties of FDH from Thiobacillus sp. KNK65MA (TsFDH) for production of formate from CO2 gas. To discover more efficient CO2-reducing FDHs than a reference enzyme, i.e. CbFDH, five FDHs were selected with biochemical properties and then, their CO2-reducing activities were evaluated. All FDHs including CbFDH showed better CO2-reducing activities at acidic pHs than at neutral pHs and four FDHs were more active than CbFDH in the CO2 reduction reaction. In particular, the FDH from Thiobacillus sp. KNK65MA (TsFDH) exhibited the highest CO2-reducing activity and had a dramatic preference for the reduction reaction, i.e., a 84.2-fold higher ratio of CO2 reduction to formate oxidation in catalytic efficiency (k cat/K B) compared to CbFDH. Formate was produced from CO2 gas using TsFDH and CbFDH, and TsFDH showed a 5.8-fold higher formate production rate than CbFDH. A sequence and structural comparison showed that FDHs with relatively high CO2-reducing activities had elongated N- and C-terminal loops. The experimental results demonstrate that TsFDH can be an alternative to CbFDH as a biocatalyst in CO2 reduction systems.  相似文献   

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