稳恒磁场作用下微生物燃料电池的产电特性和电化学阻抗谱分析

对混合菌接种的双室微生物燃料电池加载磁场强度为175 mT的稳恒磁场,利用电化学交流阻抗等电化学分析方法,考察了在磁场作用下微生物燃料电池（MFC）产电性能的变化,分析了磁场对MFC各部分内阻的影响。加载磁场使已启动完成的MFC的产电明显增强,开路电压提高了10%。加载磁场后最大功率密度为2.08 W/m2,大于加载前的1.58 W/m2,表观内阻由170Ω降至80Ω。电化学阻抗谱分析确定了阳极、阴极和全电池的等效电路模型,拟合结果发现阳极极化内阻约为5Ω。加载磁场使MFC的阴极极化内阻由74.98Ω降至56.73Ω。     

炼油废水微生物燃料电池启动及影响因素

以炼油废水为碳源,构建双室填料型微生物燃料电池,考察接种液、外接电阻等电池启动条件,以及电导率、pH值和缓冲溶液强度等溶液性质对电池产电性能的影响。利用微生物燃料处理炼油废水,COD去除率(52±4)%,含油量去除率(81.8±3)%;利用废水中存在的原生菌即可启动电池,但启动期长,外加接种液可快速启动电池;启动时外接电阻的大小对电池稳定运行后的输出功率有明显影响,对电池内阻影响相对较小,当启动外接电阻为2 000Ω,电池输出功率最大,为288 mW/m3;随阳极溶液电导率电池增大,电池内阻降低,输出功率升高;pH值变化对电池阳极电势影响较大,进而影响电池输出,当溶液pH为9时,电池输出电压最大(388 mV),pH过高或过低均不利于电池产电;随着缓冲强度的增大,电池输出电压增大,且PBS缓冲强度的增大可从电导率增大和改善质子传递条件两方面提高电池的输出功率。     

全细胞脂肪酶(菌)对SBR系统中活性污泥性能的影响

将全细胞脂肪酶(菌)以产脂肪酶微生物的形式直接投加到SBR内,与投加野生型酵母菌及空白对照进行比较,研究其对活性污泥性能及含油脂废水处理效果的影响。结果表明,在15～20℃,pH 6.5～7.5,进水油脂浓度2 000 mg/L的条件下,投加一定量全细胞脂肪酶(菌)的SBR系统间歇处理4 d,活性污泥增殖速度加快,是投加野生型酵母菌的1.3倍。静置30 min时活性污泥SV达到45%,SVI为151,MLSS最高可达2 965 mg/L左右,絮凝时间缩短且无污泥膨胀现象。投加全细胞脂肪酶(菌)的SBR系统中,油脂去除率为86.5%,COD去除率为79.5%,与投加野生型酵母菌的SBR系统相比去除率提高了1.3倍。说明投加全细胞脂肪酶(菌)后活性污泥性能增强,油脂废水处理效率提高。     

Metabolism of the14C-labeled herbicide clodinafop-propargyl in plant cell cultures of wheat and tobacco

The metabolism of ¹⁴C-clodinafop-propargyl (CfP) was examined in cell cultures of wheat (Triticum aestivum L. cv. ‘Heines Koga II’) and tobacco (Nicotiana tabacum L.). Besides the non-transgenic tobacco culture, cultures transformed separately with cDNA of human cytochrome P450-monooxygenases (P450s) CYP1A1, CYP1A2, CYP3A4, CYP2B6 and CYP2C19 were examined. Experiments with wheat were executed in the presence and absence of safener cloquintocet-mexyl (CqM). After 48 h of incubation, only about 10% of applied ¹⁴C was found in media (both tobacco and wheat). Non-extractable residues of ¹⁴C-CfP in wheat cells were 16.54% (without CqM) and 30.87% (with CqM). In all tobacco cultures, 82.41–92.46% of applied radioactivity was recovered in cell extracts. In contrast to wheat, non-extractable residues amounted only to 1.50–2.82%. As determined by radio-thin layer chromatography (TLC) and -high-performance liquid chromatography (HPLC), the parent CfP was not found in the cell extracts of wheat; in tobacco cell extracts, only traces of CfP were detected. After a hydrolysis of assumed carbohydrate conjugates of CfP derived polar ¹⁴C-labeled compounds, TLC and HPLC analysis showed that in wheat, a more complex pattern of metabolites of CfP were observed as compared to all tobacco cultures. In hydrolysates resulting from wheat, the identity of three primary products was confirmed by means of GC-EI-MS: free acid clodinafop (Cf), hydroxy-Cf hydroxylated at the pyridinyl moiety, and 4-(5-chloro-3-fluoropyridin-2-yloxy)phenol. In hydrolysates derived from all tobacco cultures, main metabolite was Cf besides only traces of further unidentified products. Differences among the different tobacco cultures (non-transgenic, transgenic) did not emerge. According to kinetics of disappearance of primary metabolite Cf as well as formation of polar soluble products and non-extractable residues, metabolization of CfP proceeded at a noticeably higher rate in wheat cells treated with safener CqM than in cells without CqM treatment. Thus, these results indicated a stimulation of CfP's metabolism by CqM, although metabolic profiles observed in CqM treated and non-treated cells (after hydrolysis) were qualitatively similar. The findings obtained from all tobacco cultures suggested that with the exception of ester cleavage to Cf, CfP cannot be metabolized by tobacco itself or by the human P450s examined.     

胞外多聚物在厌氧污泥颗粒化成核过程中的特性

以模拟啤酒废水为底物在IC反应器中进行厌氧污泥颗粒化培养,并对污泥颗粒化过程中胞外多聚物(EPS)的主要成分变化及其与细胞表面疏水性和Zeta电位之间的相互关系进行分析,以此来阐述EPS对污泥颗粒化成核的作用。研究结果表明,好氧剩余污泥在经过56 d的培养后,平均粒径由接种时的54.72μm增长到103.46μm,实现了厌氧污泥颗粒化成核过程;EPS蛋白质含量(PN)在颗粒化过程中逐渐由接种时的18.1 mg/g增至54.3 mg/g,而EPS多糖含量(PS)则无明显变化;此外,PN/PS与污泥平均粒径、细胞表面疏水性(RH)以及Zeta电位之间呈正相关关系,相关系数分别为0.9727、0.9593和0.9274。由此可推测:厌氧污泥颗粒化成核过程的主要作用成分为胞外蛋白质,其可以改变污泥细胞表面疏水性和Zeta电位,从而在厌氧污泥颗粒化过程中有着重要的促进作用。     

一体式MFC-好氧MBR运行效果及膜污染特性

膜生物反应器（MBR）是一种高效的污水处理工艺,而微生物燃料电池（MFC）能利用N0i作为电子受体进行脱氮。为解决膜生物反应器（MBR）脱氮效率低和膜污染问题,建立了一套能够进行脱氮、有效抑制膜污染的一体式MFC-好氧MBR新工艺。以开路MFC—MBR反应器为对照,对耦合系统中污水处理效果、膜污染情况进行研究。研究表明,2套系统的COD去除率均超过88％,对NH4-N的去除均达到99％。闭路MFC—MBR系统TN去除率达到69．4％,高于开路系统的55．3％。混合液的MLVSS／MLSS稳定在88％左右,同时耦合系统能够改善污泥混合液的性质,zeta电位的绝对值和粘度较开路系统有所减少,污泥颗粒平均体积粒径（233．482μm）较开路系统（94．877μm）有明显增加,膜清洗周期延长了41．17％。     

Biotransformation of Metamitron by Human P450 Expressed in Transgenic Tobacco Cell Cultures

In the present investigation, the oxidative metabolism of ¹⁴C-labeled metamitron was examined in plant cell cultures of tobacco overexpressing human P450 enzymes CYP1A1 or CYP1A2; special interest was in the aromatic hydroxylation of the herbicide. The oxidative metabolites deaminometamitron (DAM) and 4-hydroxydeaminometamitron (4-HDAM) were found in the untransformed control culture as well as in the transgenic culture. The transgenic cultures, however, exhibited higher turnover rates after 48 h of incubation with 20 μg ¹⁴C-metamitron per assay (untransformed: 40%, CYP1A1: 80%, CYP1A2: 100%). Primary metabolite 4-HDAM was partially found in glucosylated form in the transgenic cultures. As minor oxidative metabolites, 6-hydroxyphenyl-3-methoxymethyl-1,2,4-triazine-5(4H)-one and 3-hydroxymethyl-6-phenyl-1,2,4-triazine-5(4H)-one were identified in the transgenic cultures by GC-MS, LC-MS. Additionally, it could be demonstrated that both foreign enzymes (CYP1A1, CYP1A2) also catalyzed the deamination of metamitron. In a large-scale study (up to 400 μ g per assay) with the transgenic culture expressing CYP1A2, the high efficiency of this P450 system toward metamitron was demonstrated: turnover of the xenobiotic was almost complete with 400 μ g. Since large portions of unglucosylated 4-H-DAM were found, the activity of foreign CYP1A2 apparently exceeded that of endogenous O-glucosyltransferases of the tobacco cell culture. We concluded that in comparison to the nontransformed cell culture, the extent of metabolism was considerably higher in the transgenic cultures. The transgenic cell cultures expressing human CYP1A1 or CYP1A2 are thus suitable tools for the production of large quantities of primary oxidized metabolites of metamitron.     

碳纳米管对嗜酸氧化亚铁硫杆菌的毒性效应及其作用机制

以嗜酸氧化亚铁硫杆菌（Acidithiobacillus ferrooxidans）为实验菌株,探讨不同条件下碳纳米管（CNTs）对其生长的影响,并采用SEM、EDS和FT-IR等手段分析CNTs对嗜酸氧化亚铁硫杆菌的毒性机制。实验结果表明,CNTs对Acidithiobacillus ferrooxidans生长有抑制作用,并随着CNTs剂量的增加,毒性增大。在CNTs投加量为500 mg/L时,培养40 h后菌株的生长量OD420达到最大值0.117,低于空白组的0.163。培养温度和培养基的pH对CNTs的细胞毒性效应有较大影响,在菌体生长的适宜条件下（pH 3.0,温度为30℃）,CNTs对菌体的毒性最强。SEM、EDS和FT-IR分析结果显示,CNTs附着在细胞表面,与细胞表面的羟基、氨基等基团相互作用,并可能诱发菌体细胞产生活性氧自由基（ROS）,从而导致细胞死亡。     

不同氯离子浓度对电化学法处理微污染水中含氮化合物的影响

采用电化学氧化法对微污染水进行处理,在极板间距为1 cm,电解时间为10 min的条件下,通过投加NaCl溶液,使水中的NH4+及Cl-的摩尔比分别为1∶1、1∶2、1∶3,并与未投加NaCl溶液的电解出水进行比较,主要考察不同氯离子浓度对电化学法去除微污染水中的含氮化合物的效果影响.实验表明:随着氯离子浓度的不断提高...