一种新奇的甲烷氧化细菌——能兼性营养和厌氧生长的沼气甲基弯菌

经过细心的条件选择实现了无甲烷条件下甲烷氧化菌沼气甲基弯菌81Z(methylosinus methanica 81Z)利用C2化合物的生长，同时 发现二碳代谢中间产物甘氨酸的胞外积累及对生长的抑制作用。又在此基础上从81Z原种中富集得到一株菌81Z-A，兼性生长能力大 幅度提高，而且除乙酸外又能利用丙酮酸、苹果酸、柠檬酸、葡萄糖而生长。对细胞氧化各种有机底物时氧吸收的测定及酶分析结 果发现了在其它甲烷氧化细菌中未曾发现的异柠檬酸裂解酶和苹果酸酶的存在，表明81Z除了具有通常II型菌的碳代谢途径外，具 有特殊的补偿代谢途径——乙醛酸支路以及从乙酸生糖的回补途径。因此推证其兼性生长的能力是固有的，从而说明了甲烷氧化菌 的专一性概念没有普遍意义。说明了81Z还能在含有二碳的培养基中厌氧生长，包括细胞的分裂和增值行为。虽然这种厌氧生长还 很弱，但至少可以说明它不是严格好氧的，这对于传统的关于甲烷氧化菌的严格好氧的概念是一个冲击。81Z正常条件下是利用甲 烷而生长的，当供给它乙酸、乙醛酸和丝氨酸时能促进含C-C键有机物氧化的活性，而对甲烷单加氧酶和其它C2化合物的氧化有抑 制或阻遏作用，对碳同化的丝氨酸途径的关键酶羟基丙酮酸还原酶有阻抑作用。同时也证明了81Z的甲烷单加氧酶和甲醇氧化活性 可被甲烷、甲醇所诱导，而因甲酸而降低。The growth of Methylosinus methanica 81Z on C2-compounds without methane was realized by selecting suitable conditions. The intermediate product Gly from its C2 metabolism was found to accumulate out cells and inhibit its growth. 81Z-A, which was obtained from 81Z by richening, could grow on C2- compounds rapidly. It can even grow on pyruvate, malate, citrate and glucose. The results of measurements of oxygen consumption by cell suspensions in the presence of various organic compounds and the results of enzyme assays of detected activities of isocitrate lyaze and malic enzyme in cell extracts which were not found in other methantrophs showed that 81Z possesses not only the regular carbon metabalic pathways but also some peculiar anaplerotic pathways--the glyoxylate cycle and the gluconeogenic pathway from acetate. As a consequence of these studies, its ability of facultative growth is inherent. Therefore, the concept of obligate dependence on C2- compounds of methanotrophs is not of universal significance. The ability of 81Z's growth(including desintegration and proliferation behaviour) on C2-compounds anaerobically was also demonstrated. Despite of the weakness of this growth, at least it could be said that 81Z is not strictly aerobic. This is a strike to the traditonal concept about the strictly aerobic action of methanotrophs. Regularly, 81Z grows on methane. The presence of acetate, glyoxylate and serine could increaze its ability of oxidizing the organic coumpounds containing C-C ponds. In contrast, they could inhibit the activities of MMO and other C2-compounds oxidation, they also repressed the key enzyme hydroxypyruvate reductase of the serine-pathway for carbon assimilation. At the some time, it was testified that the activities of MMO and methanol oxidation were inducible by methane or methanol and were lower in the presence of formate.

猪场废水短程硝化反硝化-厌氧氨氧化脱氮研究

畜禽废水是农村水环境污染的主要来源之一，其处理的难点在于脱氮。传统生物脱氮法具有能耗高、需大量外加碳源等缺点，开发低成本、高效率的新型生物脱氮技术具有重要意义。 本研究将短程硝化反硝化和厌氧氨氧化两种脱氮新技术结合，让前者为后者创造去除可降解COD、降低总氮负荷、调整pH、调整氨氮和亚硝酸盐氮浓度比例等进水条件，而后者可在无需外加碳源的条件下进一步脱氮，二者结合可成为高氨氮、低C/N废水脱氮的新途径。 试验以低碳氮比猪场废水为研究对象，首先进行了短程硝化反硝化预处理研究，同时启动并运行调控厌氧氨氧化反应器，最后以经过短程硝化反硝化预处理的猪场废水为进水，进行厌氧氨氧化脱氮考察。实验表明：（1）短程硝化反硝化作为厌氧氨氧化的预处理工序是可行的。猪场废水通过短程硝化反硝化，可以达到基本去除可生化COD、部分脱氮、控制出水氨氮和亚硝酸盐氮浓度之比在1︰1左右、pH在7.5～8.0的目的， COD和总氮平均去除率分别为64.3%、49.1%,出水可达到厌氧氨氧化反应的进水要求。（2）采用模拟废水启动厌氧氨氧化反应器，经过5个月左右的运行调控，反应器启动成功并稳定运行，最高总氮去除率为87.1%，总氮容积去除率最高达到0.14kg/m3.d；整个稳定阶段，氨氮、亚硝酸盐氮、硝酸盐氮的变化量之比为1︰1.21︰0.33。（3）经过短程硝化反硝化预处理的猪场废水厌氧氨氧化脱氮效果稳定，氨氮、亚硝酸盐氮、总氮、COD的平均去除率分别为93.0%、99.4%、84.6%、18.1%，处理效果与模拟废水处理系统相比无明显变化。（4）经过短程硝化反硝化预处理后，猪场废水中残留有机物成分在厌氧氨氧化反应过程中无显著变化，主要为酯类和烷烃类物质；残留有机物对厌氧氨氧化效果无明显影响。（5）采用PCR技术进行特殊功能菌种检测，结果表明模拟废水处理系统和猪场废水处理系统的菌群中均含有厌氧氨氧化菌和好氧硝化菌；通过blast比对，厌氧氨氧化菌扩增序列与未培养的Planctomycetales菌和Candidatus Brocadia fulgida菌16S rRNA部分序列相似性分别为95％、90%。（6）MPN法菌种计数结果显示，模拟废水处理系统和猪场废水处理系统的菌群中均含有硝化细菌、亚硝化细菌和少量反硝化菌，实验条件下的微生物系统是一个厌氧氨氧化菌与好氧硝化菌、反硝化菌共存的系统。 Poultry wastewater is one of the main source of water pollution in rural areas，and nitrogen removal is the most difficult part in treating poultry wastewater. There are some disadvantages in traditional nitrogen removal, such as high energy consumption and more additional organic carbon. It is important to develop ecolomical and efficient technologyies. Shortcut nitricfication/denitrification, as a pretreatment process, was combined with Anammox in this research, so that part of total nitrogen and most degradable COD could be removed by the former, and further nitrogen removal could be implemented by the latter. The combination of the two technologies was a new approach to treat wastewater with high ammonium and low C/N. Piggery wastewater with low C/N was treated in lab-scale experiment. Firstly, shortcut nitrification/denitrification was investigated, and Anammox reactor was started up successfully at the same time. Then piggery wastewater after pretreatment was treated by Anammox. The results showed :(1) It was feasible to take nitrification/denitrification as the pretreatment process of Anammox. By using this process, part of total nitrogen and COD were removed, the ratio of ammonium and nitrite reached around 1︰1 and the pH was about 7.8, which were favorable for Anammox. The average removal percentage of COD and total nitrogen were about 64.3% and 49.1%, respectively. (2) Simulated wastewater was used to start up Anammox reactor. The reactor was started up successfully within 5 months and stable performance was achieved. The highest nitrogen removal reached 87.1% and the biggest volumetric total nitrogen removal rate reached 0.14kg/m3.d. The average ratio of ammonium, nitrite and nitrate was 1:1.21:0.33. (3)Taking the effluent of shortcut nitrification/denitrification as the influent, the nitrogen removal efficiency of Anammox was stable, and the the average removal percentage of ammonium, nitrite, total nitrogen and COD were 93.0%, 99.4% , 84.6% and 18.1%, respectively, which had little difference with that by using simulated wastewater..(4) After pretreatment, the residual organic carbon in piggery wastewater showed no obvious change during the Anammox process, and the main organic compounds were saturated hydrocarbon and ester, which had no obvious negative effect on Anammox process.(5) By PCR technology, the existence of Anammox bacteria was confirmed and the aerobic nitrifying bacteria was found to coexist as well. The result of blast showed that the identities of Anammox bacterium to part of 16S rRNA sequence of uncultured Planctomycetales bacterium and Candidatus Brocadia fulgida bacterium were 95% and 90%, respectively.（6）By MPN method, nitrite oxidizer, ammonium oxidizer and denitrification bacteria were detected in both simulated and piggery wastewater treatment system of Anammox, and the microorganism system was composed of Anammox bacteria，aerobic bacteria and denitrification bacteria together.

Recent progress in adsorbed stationary phases for capillary electrochromatography

This review surveys the recent progress in the adsorbed stationary phases for capillary electrochromatography (CEC). Adsorption-based methods for preparation of stationary phase are novel approaches in CEC, which allow rapid and facile preparing stationary phases with desirable selectivity onto an open-tubular fused-silica capillary, a baresilica or ion-exchange packed column or a monolithic silica or polymer column. A variety of adsorbing agents have been developed as adsorbed stationary phases, including ionic long-chain surfactant, protein, peptide, amino acid, charged cyclodextrin (CD), basic compound, aliphatic ionene, and ion-exchange latex particle. The adsorbed stationary phases have been applied to separation of neutral, basic and acidic organic compounds, inorganic anions and enantiomers. They have also been applied to on-line sample concentration, fast separation and study of the competitive binding of enantiomers with protein.

Determination of photochemically produced hydroxyl radicals in seawater and freshwater

A variety of short-lived, reactive chemical species (i.e. free radicals and excited state species) are known to be photochemically produced in natural waters. Some of these transients may strongly affect chemical and biological processes, and they have been implicated in the degradation of organic pollutants and natural organic compounds in aqueous environments. Previous studies demonstrated that the highly reactive hydroxyl radical (OH) is photochemically formed in seawater. However, the quantitative importance of this key species in the sea has not been previously studied because of past analytical limitations. By using a highly sensitive probe based on α-H atom abstraction from methanol, we were able to measure production rates and steady-state concentrations of photochemically produced OH radicals in coastal and open ocean seawater and freshwaters. The validity of the method was tested by intercalibrating with an independent, OH-specific reaction, hydroxylation of benzoic acid, and also by competition kinetics experiments. Our OH production rates and steady-state concentrations for freshwaters are in excellent agreement with those measured by previous investigators for similar waters. In contrast, for seawater, the values we measured are 1–3 orders of magnitude higher than previously predicted by models, indicating that there is a major unknown photochemical OH source (s) in seawater.

Gas-aerosol partitioning of semi volatile carbonyls in polluted atmosphere in Hachioji, Tokyo

Gaseous and particulate semi volatile carbonyls have been measured in urban air using an annular denuder sampling system. Three dicarbonyls, five aliphatic aldehydes and two hydroxy carbonyls were observed. Concentrations of other biogenic and anthropogenic volatile organic compounds (VOCs), SO2, CO, NO2 and particle concentration were also measured. Estimated gas-aerosol equilibrium constants for the carbonyls showed an inverse correlation with the concentrations of anthropogenic pollutants such as benzene, isopentane and SO2. This suggests that the increase in the fraction of non-polar anthropogenic particles in the atmosphere could change the average property of the ambient aerosols and drive the gas particle equilibrium of the carbonyls to the gas phase. This trend is uncommon in remote forest air. In this study, we examined the factors controlling the equilibrium in the polluted atmosphere and show that there is a difference in gas-aerosol partition between polluted and clean air.

Silica Materials Doped with Bifunctional Ionic Liquid Extractant for Yttrium Extraction

Two new silica-based organic-inorganic hybrid materials (B104SGs and O104SGs) doped with a binary mixture of imidazolium and phosphonium ionic liquids have been synthesized and used as sorbents in batch system for rare earths (RE) separation. Imidazolium ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate (C(4)mim(+)PF(6)(-)) or 1-octyl-3-methylimidazolium hexafluorophosphate (C(8)mim(+)PF(6)(-)) acted as porogens to prepare porous materials and additives to stabilize extractant within silica gel.

The algorithm on automated aromaticity perception of molecules

It is important to detect the aromaticity of structures during the process of structure elucidation and output. In this paper, an alogrithm was proposed to detect the aromaticity of structures by the use of algorithm on ring identification. The results show that it could be used to identify most of the aromatic structure. It have been used as constraints of Expert System on Elucidation Structure of Organic Compounds(ESESOC) and a good result has been achieved.

Prediction of molar absorptivities of color reagents and their color reactions with yttrium by artificial neural networks

The new topological indices A(x1)-A(x3) suggested in our laboratories were applied to the study of structure-property relationships between color reagents and their color reactions with yttrium. The topological indices of twenty asymmetrical phosphone bisazo derivatives of chromotropic acid were calculated. The work shows that QSPR can be used as a novel aid to predict the molar absorptivities of color reactions and in the long term to be helpful tool in-color reagent design. Multiple regression analysis and neural network were employed simultaneously in this study. The results demonstrated the feasibility and the effectiveness of the method.

A QSAR of the toxicity of amino-benzenes and their structures

The quantum chemical parameters and the topological indices have been calculated for the prediction of the toxicity of amino-benzenes in the environment, and work has been done on the multiple regression and neural networks. The combination of CoMFA with formation heat yields greatly improved results. A good model has been obtained which provides a basis for the studies of the toxic action mechanism.

Comparison of different methods for variable selection

In chemistry for chemical analysis of a multi-component sample or quantitative structure-activity/property relationship (QSAR/QSPR) studies, variable selection is a key step. In this study, comparisons between different methods were performed. These methods include three classical methods such as forward selection, backward elimination and stepwise regression; orthogonal descriptors; leaps-and-bounds regression and genetic algorithm. Thirty-five nitrobenzenes were taken as the data set. From these structures quantum chemical parameters, topological indices and indicator variable were extracted as the descriptors for the comparisons of variable selections. The interesting results have been obtained. (C) 2001 Elsevier Science B.V. All rights reserved.

Application of acetone and dimethyl ether chemical ionization reagent gases to structural analysis

Acetone and dimethyl ether( DME) have been shown to be reagent gases of exceptional utitlity and versatility for the characterization of a variety of class of organic compounds. The fragmentation mechanisms of the adduct product ions, formed by ion/molceule reaction of the substrate with the ionized gases, have been studied and substantiated by experiments with acetone-d(6) and DME-d(6).

Computer perception of topological symmetry by all-paths algorithm

During the development of our ESESOC system (Expert System for the Elucidation of the Structures of Organic Compounds), computer perception of topological symmetry is essential in searching for the canonical description of a molecular structure, removing the irredundant connections in the structure generation process, and specifying the number of peaks in C-13- and H-1-NMR spectra in the structure evaluation process. In the present paper, a new path identifier is introduced and an algorithm for detection of topological symmetry from a connection table is developed by the all-paths method. (C) 1999 Elsevier Science B.V. All rights reserved.