初始底物浓度及pH对丁酸梭菌T4发酵木糖产氢的影响

本研究采用间歇培养方式对丁酸梭菌T4发酵木糖进行产氢研究,考察初始pH和初始底物浓度对其产氢特性的影响。结果表明,菌株T4在初始pH5.0～8.5及初始底物浓度5～40g/L时均可以产氢,其累积产氢量和最大比产氢速率随着pH及底物浓度的增加均呈现先增加后减少的趋势。在pH6.5和底物浓度20g/L时,比产氢速率和累积产氢量达到最大,分别为4.26L/L和18.86mmol-H2/hg-DCW,而后随着pH或者底物浓度的增加二者均呈现减少的趋势;在pH6.5和底物浓度15g/L时,得到最大值比产氢量为2.17mol/mol-木糖。而在不同的pH下,发酵产生的液态产物主要是乙酸和丁酸,其中在pH小于6.0时,有少量的丙酸生成,而在pH大于6.0时,则有乙醇生成。     

啤酒废水的厌氧发酵产氢

对经热处理后的厌氧污泥利用啤酒废水厌氧产氢的影响因素（温度、初始pH值和有机物浓度）进行了研究。结果表明,温度与初始pH值对厌氧产氢过程均有显著影响。最佳温度为35℃,此时,比产氢速率、氢气产率、VFA含量与总糖降解率均达到最大,分别为10.16mL/g-VSS.h、0.1673mL/mg.COD、4640.0mg/L和95.20%。最适初始pH值为6.0～7.0,在此范围内氢气产率、VFA含量、总糖降解率均可获得最大值。一个半经验模型适用于描述初始pH值与氢气产率之间的相互关系。在35℃、初始pH值6.5的条件下,有机物浓度COD1000mg/L～2000mg/L时,总糖降解率与VFA产率均获得最大值。底物抑制模型分析结果显示COD1587mg/L时,氢气产率（0.1935mL/mg.COD）达到最大。     

固定化光合细菌利用有机物产氢的研究

应用固定化细胞技术包埋荚膜红假单胞菌(Rhodopseudomonas capsulata)菌株386．研究在光照下利用有机物产氢的特性。实验观察到,光照培养120小时,悬浮培养物的产氢量为68．2ml·比产氢速率为104．1ml H2/g(生物量)·h;用琼脂包埋后．其产氢能力得到改善,产氢量和比产氢速率分别达到128．4ml和l 9s．8mlH2/g·h。该菌株除可利用苹果酸外,还可利用葡萄糖、乳酸、丙酸等基质高效地产氢。基质浓度只有控制在适当水平时,才具有较高的基质转化产氢效率。此外．菌体生物量、菌龄、培养液pH、光照强度、光照／黑暗时间比以及温度对产氢过程均有不同程度的影响。     

微生物烟气脱硫中硫酸盐还原阶段的限制性因素及其影响

【目的】利用硫酸盐还原菌(SRB)厌氧活性污泥进行烟气脱硫,探索硫酸盐生物还原的最适条件及重金属离子对硫酸盐生物还原的影响,以提高硫酸盐还原阶段的效率。【方法】对取自污水处理厂的SRB厌氧活性污泥进行高浓度硫酸盐胁迫驯化。分析生物脱硫过程中SRB厌氧污泥还原硫酸盐的限制性因素及影响。【结果】在最适生长条件下(pH 6.5,32°C),经驯化获得的SRB厌氧活性污泥有较强的硫酸盐还原能力。Fe2+的适量添加对硫酸盐还原有一定促进作用。SRB厌氧污泥还原硫酸盐的ThCOD/SO42-最适值为3.00,ThCOD=3.33为最适理论化学需氧量,硫酸盐还原率可达72.15%。SRB厌氧污泥还原硫酸盐反应体系中抑制SRB活性的硫化物浓度为300 mg/L。Pb2+和Ni2+在较低的浓度下(1.0 mg/L和2.0 mg/L)对硫酸盐的还原产生较强的抑制作用,而Cu2+在稍高的浓度下(8.0 mg/L)显示出明显的抑制作用。【结论】经驯化,SRB厌氧活性污泥显示出较强的硫酸盐还原能力,具有应用于工业烟气生物脱硫的潜力。去除重金属离子Pb2+、Ni2+和Cu2+可有效解除对硫酸盐生物还原作用的抑制。     

氯仿处理厌氧污泥发酵制氢中微生物多样性的解析

研究了不同浓度氯仿对厌氧污泥产氢及其微生物多样性的影响。在氯仿浓度为0.050%时,累积氢、氢气产率、VFA和总糖降解率均达到最大,分别为639mL、1.71molH2/mol消耗葡萄糖、2880mg/L和85%。利用PCR-DGGE技术对不同浓度氯仿处理的污泥样品中微生物多样性和种群结构进行分析显示,4个细菌克隆属于Clostridia,2个细菌克隆分别属于Acidobacteria和δ-proteobacteria,其他4个均属于不可培养细菌。Clostridia中的4个菌群均属产氢菌群,条带7中含有的细菌可能属于HPB。发酵产氢后的污泥样品C3(氯仿浓度=0.05%)中细菌类型主要有:Megasphaera sueciensis、Megasphaera paucivorans、Clostridium cellulosi、Clostridium sp.和不可培养细菌,为最适产氢群落结构。     

产氢菌的复合诱变选育及突变株HCM-23的产氢特性

以厌氧产氢细菌Clostridium sp.H-61为原始菌株,先后经亚硝基胍(NTG)、紫外(UV)诱变,选育得到1株高产突变株HCM-23.在葡萄糖浓度为10 g/L的条件下,其产氢量为3024 mL/L,比原始菌株提高了69.89%;其最大产氢速率为33.19 mmol H2/g DW·h,比原始菌株(19.74 mmolH2/g DW·h)提高了68.14%.经过多次传代试验,稳定性良好.其发酵末端产物以乙醇和乙酸为主,属于典型乙醇型发酵代谢类型.其最适产氢初始pH为6.5,最适生长温度为36℃,以蔗糖为最佳碳源.与原始菌株相比,突变株HCM-23的产氢特性发生了改变,如生长延滞期延长,可利用无机氮源等.     

酸驯化和紫外诱导提高微藻耐酸性

应用微藻固定烟道气CO2既可减排又能生产高值生物基产品,但是,烟道气高浓度CO2和氮硫氧化物导致培养液过度酸化、抑制微藻生长。通过建立微藻抗性驯化简易方法,以期提高微藻耐酸性和在低p H条件下的起始生长速率。经过酸驯化和紫外诱导叠加处理后的栅藻(Scenedesmus),在酸性环境下生长初期的平均生长速率达到0.253 g/(d·L),明显高于单因子处理的p H4.5酸驯化(0.132 g/(d·L))和紫外诱导5 min(0.092 g/(d·L))的生长速率。经过驯化处理的种子藻在p H3的酸性环境中可以正常生长,而未驯化微藻生长近乎停滞。经过驯化处理的种子藻接入低p H培养基后起始生长速率比未驯化微藻提高6.6倍。酸驯化和紫外诱导处理显著提高了栅藻对低p H环境的耐受性。     

产氢菌的复合诱变选育及突变株HCM-23的产氢特性

以厌氧产氢细菌Clostridium sp. H-61为原始菌株, 先后经亚硝基胍(NTG)、紫外(UV)诱变, 选育得到1株高产突变株HCM-23。在葡萄糖浓度为10 g/L的条件下, 其产氢量为3024 mL/L, 比原始菌株提高了69.89%; 其最大产氢速率为33.19 mmol H2/g DW·h, 比原始菌株(19.74 mmol H2/g DW·h)提高了68.14%。经过多次传代试验, 稳定性良好。其发酵末端产物以乙醇和乙酸为主, 属于典型乙醇型发酵代谢类型。其最适产氢初始pH为6.5, 最适生长温度为36℃, 以蔗糖为最佳碳源。与原始菌株相比, 突变株HCM-23的产氢特性发生了改变, 如生长延滞期延长, 可利用无机氮源等。     

高效降解机油微生物的筛选及除油效果初探

从多处受石油及其制品污染的土壤中筛选到六株对高浓度机油等相关石油制品具有降解能力的微生物菌种。对该六株菌种的单独和混合降解机油的效果进行了研究,并考察了营养成分对机油降解的影响。实验表明:Px01菌种具有最强的除油能力,在合适条件下,Px01培养液的机油降解速率可达0.502g/L.d。混合菌的除油效果明显好于单菌,最高降解速率可到0.64g/L.d。混合菌的营养要求较低,添加有机营养元素对混合微生物的生长和机油降解没有显著的促进作用。由于所筛选驯化得到的微生物菌种针对高浓度含机油废水的降油效果显著,因此具有良好的应用前景。     

城市污泥中邻苯二甲酸酯(PAEs)的厌氧微生物降解

邻苯二甲酸酯(PAEs)是城市污泥中普遍存在的一类具有内分泌干扰性作用的有机污染物.研究污泥厌氧生物处理过程中PAEs的微生物降解对保障污泥农用的安全性十分必要.本文以污泥中两种主要的PAEs——邻苯二甲酸二丁酯(DBP)和邻苯二甲酸(2-乙基己)酯(DEHP)为研究对象,通过比较PAEs在污泥厌氧消化系统与发酵产氢系统中降解过程的差异及系统污泥特性的变化,分析不同污泥厌氧生物处理系统中影响PAEs降解的可能因素.结果表明: 在污泥厌氧发酵系统中,DBP在6 d内降解率达99.6%, DEHP在整个14 d的培养期间也降解了46.1%;在发酵产氢系统中,在14 d培养过程DBP的降解率仅为19.5%,DEHP则没有明显的降解.与厌氧消化系统相比,PAEs在发酵产氢系统中的降解受到明显抑制,这与发酵产氢过程中微生物量下降、革兰氏阳性菌/革兰氏阴性菌(G⁺/G^-)和真菌/细菌变小及挥发性脂肪酸(包括乙酸、丙酸及丁酸)浓度升高有关.     

The Synthesis of Moraprenyl and Dolichyl Hydrogen Succinates and Maleates

The reactions of moraprenol and dolichol with succinic and maleic anhydrides in the presence of pyridine or triethylamine were studied, and the conditions were found for the efficient synthesis of moraprenyl and dolichyl hydrogen succinates and maleates. These may be of interest as analogues of moraprenyl and dolichyl hydrogen phosphates with modified anionic groups.     

Effects of Formate on Fermentative Hydrogen Production by Enterobacter aerogenes

This paper describes the effects of formate on fermentative hydrogen production by Enterobacter aerogenes by way of batch culture. When 20 mM formate was added to pH 6.3 and pH 5.8 E. aerogenes glucose cultures (formate culture) at the beginning of cultivation, hydrogen evolution through both glucose consumption and decomposition of the extrinsic formate occurred together, while hydrogen evolution occurred only through glucose consumption in the control cultures. The hydrogen evolution rates in the formate cultures were faster than in the control cultures, although cell growth and glucose consumption rates in the formate cultures were slower than the control cultures’. The decomposition rate of the extrinsic formate in the pH 5.8 formate culture was faster than in the pH 6.3 fomiate culture. The hydrogen yield from glucose in the pH 6.3 formate culture increased due to the increasing amount of the nicotinamide adenine dinucleotide for hydrogen production.     

干旱条件下大豆叶片H_2O_2代谢变化及其同抗旱性的关系

干旱条件下大豆叶片H_2O_2含量增加,AsA POD与 GR活性均表现“先上升后下降”的趋势。叶片AsA与GSH含量均随干旱时间的延长而逐渐下降,而PPOD活性则持续增加。抗旱性较强的小粒大豆品种7605在干旱条件下能维持较强的 H_2O_2清除能力,H_2O_2累积较少。     

SURVEY OF SELECTED SEA WEEDS FOR SIMULTANEOUS PHOTOPRODUCTION OF HYDROGEN AND OXYGEN1

Ten seaweed species were surveyed for simultaneous photoevolution of hydrogen and oxygen. In an attempt to induce hydrogenase activity (as measured by hydrogen photoproduction) the seaweeds were maintained under anaerobiosis in CO₂-free seawater for varying lengths of time. Although oxygen evolution was observed in every alga studied, hydrogen evolution was not observed. One conclusion of this research is that, in contrast to the microscopic algae, there is not a single example of a macroscopic alga for which the photoevolution of hydrogen has been observed, in spite of the fact that there are now at least nine macroscopic algal species known for which hydrogenase activity has been reported (either by dark hydrogen evolution or light-activated hydrogen uptake). These results are in conflict with the conventional view that algal hydrogenase can catalyze a multiplicity of reactions, one of which is the photoproduction of molecular hydrogen. Two possible explanations for the lack of hydrogen photoproduction in macroscopic algae are presented. It is postulated that electron acceptors other than carbon dioxide can take up reducing equivalents from Photosystem I to the measurable exclusion of hydrogen photoproduction. Alternatively, the hydrogenase system in macroscopic algae may be primarily a hydrogen-uptake system with respect to light-activated reactions. A simple kinetic argument based on recent measurements of the photosynthetic turnover times of simultaneous light-activated hydrogen and oxygen production is presented that supports the second explanation.     

Isolation and characterization of low hydrogen sulphide producing wine yeast

Variants of the wine yeast Saccharomyces cerevisiae var. montrachet no. 522 which retain more and excrete less hydrogen sulphide (H₂S) into the growth medium have been isolated and characterized. Wine produced using these low excretors has been found to contain less H₂S.     

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。     

崭露头角的氢气生物学

氢气（hydrogen gas,H₂）是新发现的生物气体信号分子。自2007年开始,有关H₂的生理调控活性及信号转导功能受到广泛的关注,并逐步形成了研究氢气生物学效应和分子机理的一门新学科--氢气生物学。按照实际运用范围的不同,氢气生物学也可以划分为氢医学和氢农学。在医学方面,通过多种动物模型研究和部分临床试验,发现H2具有抗氧化、抗炎和抗凋亡的作用,而且H₂对缺血/再灌注以及以炎症为基础的急性组织缺血性疾病和慢性退行性疾病（如帕金森病、阿尔茨海默病和动脉粥样硬化等氧化应激相关疾病）均具有较为理想的正面效果。在农学方面,相关报道还发现H₂可以提高苜蓿、水稻和拟南芥对非生物胁迫的耐性,调控黄瓜、番茄、猕猴桃、芽苗菜、黑大麦和食用菌的生长发育和营养品质,延长洋桔梗、玫瑰和百合切花的保鲜以及提高家畜对病原微生物的抗性。本文首先探究了氢气生物学的发展历史,提出氢医学研究思路的源头是电解水,结合H₂测定方法、内源H₂的产生途径以及氢气生物学效应的分子机理和信号转导的研究成果,从给氢方式、生物学效应以及安全性等方面,介绍了氢医学和氢农学的现状,提出选择性抗氧化机制不能完全解释现有的氢生物学效应,反映相关分子机制的复杂性和多样性。最后,针对氢气生物学的若干重要的科学和实践问题进行了展望,并提出氢医学的进一步发展还依赖于大量且可信度高的临床试验,氢农业还需要完成多年多点的大规模大田实践。     

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。     

厌氧发酵法生物制氢的研究现状和发展前景

氢气是一种理想的能源,具有转化率高、可再生和无污染等优点。与传统制氢方法相比,生物制氢技术的能耗低,对环境无害,其中的厌氧发酵生物制氢已经越来越受到人们的重视。本文主要介绍了厌氧发酵生物制氢技术的方法和机理,分析了生物制氢的可行性,结合国内外研究现状提出了未来的发展方向。     

Preparation and utilization of a reagent for the isolation and purification of low-molecular-mass thiols

Problems inherent in the isolation of thiols from natural sources, such as oxidation, undesirable addition reactions, and low concentration of thiol species in cell-free extracts, can be circumvented by reversible derivatization to a less labile form which can be concentrated selectively. These objectives are realized by converting thiols to heterodisulfides in which the thiol partner is an apolar thiol with strong affinity for hydrophobic stationary phases. When reacted with 2-S-(2(')-thiopyridyl)-6-hydroxynaphthyldisulfide at pH<5, where most thiol species are relatively stable to atmospheric oxidation, mixed disulfides with 2-mercapto-6-hydroxynaphthalene as the apolar partner are obtained in good yield and can be concentrated onto a hydrophobic stationary phase. Such heterodisulfides exhibit excellent chromatographic properties when separated on reversed-phase media and the derivatization reaction can, therefore, be conveniently monitored. Following their isolation as the heterodisulfides the thiol species of interest are recovered by reduction and facile separation from the apolar 2-mercapto-6-hydroxynaphthalene partner.