基因工程菌生物强化膜-生物反应器工艺启动期影响因素研究

基因工程菌生物强化膜-生物反应器工艺经过启动期之后,可以实现对阿特拉津的高效稳定去除,去除率在90%以上.不同条件下,启动期最短2 d,最长可达12 d.阿特拉津初始进水负荷、运行温度和工程菌接种密度,对启动期具有显著影响.增加阿特拉津初始进水负荷、提高运行温度和增加基因工程菌接种密度,可以实现快速启动.进水水质对启动期影响不大,在人工配水和实际污水2种进水条件下,启动期基本相同,而且稳定期2种进水的阿特拉津去除情况也没有差异,说明进水水质对启动期和稳定期阿特拉津的去除影响都不大.     

The joint effects of sulfonamides and their potentiator on Photobacterium phosphoreum: differences between the acute and chronic mixture toxicity mechanisms

Organisms are typically exposed to mixtures of chemicals over long periods of time; thus, chronic mixture toxicity analysis is the best way to perform risk assessment in regards to organisms. However, most studies focus on the acute mixture toxicity. To investigate the difference between chronic mixture toxicity and acute mixture toxicity, Photobacterium phosphoreum were exposed to chronic (24 h exposure) and acute (15 min exposure) toxicity of single sulfonamide (SA) and their potentiator (trimethoprim, TMP), both individually and mixtures (SA with TMP). A comparison of chronic vs. acute mixture toxicity revealed the presence of an interesting phenomenon, that is, that the joint effects vary with the duration of exposure; the acute mixture toxicity was antagonistic, whereas the chronic mixture toxicity was synergistic. Based on the approach of Quantitative Structure Activity Relationships (QSARs) and molecular docking, this phenomenon was proved to be caused by the presence of two points of dissimilarity between the acute and chronic mixture toxicity mechanism: (1) the receptor protein of SAs in acute toxicity was Luc, while in chronic toxicity it was Dhps, and (2) there is a difference between actual concentration of binding-Luc in acute toxicity and individual binding-Dhps in chronic toxicity. This deep insight into the difference between chronic and acute mixture toxicity will benefit environmental science, medical science, and other disciplines. The existence of these differences poses a challenge for the assessment of routine combinations in medicine, risk assessment, and mixture pollutant control, in which, previously, only a synergistic effect has been observed between SA and their potentiator.     

两种介体物质在漆酶降解磺胺类抗生素中的作用

通过比较两种介体物质丁香醛(SA)和1-羟基苯并三氮唑(HBT)对漆酶降解5种典型磺胺类抗生素的影响,考察了介体的起始浓度、pH值、反应温度、漆酶起始浓度等因子的影响,得到介体SA对漆酶催化降解磺胺类抗生素的效果更好.在漆酶+SA反应体系中,反应体系pH值为5~6,反应温度为30℃,SA起始浓度为0.5mmol/L,漆酶起始浓度为0.5mg/mL时,漆酶对5种磺胺类抗生素的降解效果最佳,降解去除率在15min时达到75%左右,1h内均达到97%以上. 本研究表明,适当的介体物质可大大提升漆酶对磺胺类抗生素的降解效果.漆酶在介体物质的作用下对抗生素类污染物的生态净化具有良好的应用潜力.     

Comparison of sensitivity analysis techniques: A case study with the rice model WARM

The considerable complexity often included in biophysical models leads to the need of specifying a large number of parameters and inputs, which are available with various levels of uncertainty. Also, models may behave counter-intuitively, particularly when there are nonlinearities in multiple input-output relationships. Quantitative knowledge of the sensitivity of models to changes in their parameters is hence a prerequisite for operational use of models. This can be achieved using sensitivity analysis (SA) via methods which differ for specific characteristics, including computational resources required to perform the analysis. Running SA on biophysical models across several contexts requires flexible and computationally efficient SA approaches, which must be able to account also for possible interactions among parameters. A number of SA experiments were performed on a crop model for the simulation of rice growth (Water Accounting Rice Model, WARM) in Northern Italy. SAs were carried out using the Morris method, three regression-based methods (Latin hypercube sampling, random and Quasi-Random, LpTau), and two methods based on variance decomposition: Extended Fourier Amplitude Sensitivity Test (E-FAST) and Sobol’, with the latter adopted as benchmark. Aboveground biomass at physiological maturity was selected as reference output to facilitate the comparison of alternative SA methods. Rankings of crop parameters (from the most to the least relevant) were generated according to sensitivity experiments using different SA methods and alternate parameterizations for each method, and calculating the top-down coefficient of concordance (TDCC) as measure of agreement between rankings. With few exceptions, significant TDCC values were obtained both for different parameterizations within each method and for the comparison of each method to the Sobol’ one. The substantial stability observed in the rankings seem to indicate that, for a crop model of average complexity such as WARM, resource intensive SA methods could not be needed to identify most relevant parameters. In fact, the simplest among the SA methods used (i.e., Morris method) produced results comparable to those obtained by methods more computationally expensive.     

用于处理冲厕海水的固定化生物硅藻土小球的制备

选用聚乙烯醇（PVA）和海藻酸钠（SA）混合物作为包埋载体,对筛选出的耐盐复合菌群固定化制备方法进行了研究。通过正交实验分别研究了包埋载体不同配比、包菌量、硅藻土投加量和交联时间对固定化生物硅藻土小球的性能及其对冲厕污水中COD去除效果的影响。研究结果表明,固定化生物硅藻土小球最佳包埋条件是：聚乙烯醇9％,海藻酸钠0．5％,包菌量l：1,硅藻土20g／L,交联时间为24h。在该条件下,小球成球效果较好,机械强度高,对海水冲厕污水中COD的去除率达86．95％。     

绿色荧光蛋白标记阿特拉津降解基因工程菌的特性

通过转化绿色荧光蛋白基因质粒,对阿特拉津降解基因工程菌进行标记.转化后,绿色荧光蛋白在细胞内表达情况良好.在含抗生素的LB培养基中,绿色荧光蛋白的表达水平高于LB培养基和基础培养基.在细胞生长的稳定期,绿色荧光蛋白表达水平高于停滞期和对数生长期.绿色荧光蛋白基因质粒转化和表达,不会对基因工程菌原有的降解能力产生影响,而且绿色荧光蛋白的表达水平和降解活性存在接近线形的正相关关系.荧光蛋白标记细胞投加到反应器活性污泥中,会以2种状态存在:游离态和附着态,而且初期游离态细胞的数量大于附着态细胞的数量.     

XDLVO理论解析不同离子条件下海藻酸钠微滤膜污染

应用extended Derjaguin-Laudau-Verwey-Overbeek(XDLVO)理论定量解析海藻酸钠微滤膜污染中界面微距作用力,探讨不同离子条件对膜污染影响的主控机制.结果表明,对于亲水性膜表面,范德华力促进膜污染,极性作用力阻碍膜污染;而对于疏水性膜表面,范德华力减缓膜污染,极性作用力加速膜污染.海藻酸钠与微滤膜接触时双电层作用力对膜污染贡献相对微弱.离子强度及钙离子对海藻酸钠微滤膜污染的影响主要是通过改变极性作用力来实现的.较高的离子强度会降低极性作用力的排斥性或升高极性作用力的吸引性,从而加重海藻酸钠微滤膜污染.虽然钙离子使出水通量急速下降,但钙离子的存在使得物理清洗效率提高.不同离子条件下初始阶段及后期阶段污染趋势K分别与膜-海藻酸钠粘附自由能及海藻酸钠-海藻酸钠粘聚自由能具有良好的线性相关性,表明XDLVO理论适用于描述不同离子条件下海藻酸钠微滤膜污染行为.