高铁酸钾氧化去除饮用水中微量苯酚的研究

采用次氯酸盐氧化法合成高铁酸钾,测试了其对水中苯酚的氧化去除效果及其影响因素.结果表明,苯酚的去除效率主要取决于高铁酸钾和苯酚的质量比.在酸性条件下高铁酸钾对苯酚的去除效果较好.高铁酸钾与苯酚反应主要发生在最初的几分钟时间内,是一个由快而慢的过程.     

高铁酸钾/PAC 氧化-混凝去除水体中铜绿微囊藻

铜绿微囊藻（Microcystis aeruginosa）是常见的水华种类。水华爆发时生态系统的结构和功能遭到破坏,同时产生毒素,因此研究微囊藻及其毒素的去除具有重要的意义。研究不同浓度的高铁酸钾与PAC 高铁酸钾与PAC 单独和协调去除水体中铜绿微囊藻和微囊藻毒素（Microcystin-LR,MC-LR）的去除效果。结果表明,采用高铁酸盐预氧化铜绿微囊藻,再通过PAC混凝协同作用,明显优于单独使用PAC混凝效果。20 mg×L-1高铁酸钾处理后水体中MC-LR含量降低,当高铁酸钾浓度升高至40 mg×L-1时候MC-LR 含量增加,但高铁酸钾浓度升高（100 mg×L-1）水体中MC-LR 减少;当8 mg×L-1高铁酸钾和8-16 mg×L-1PAC 联合作用时,不仅絮凝沉降藻细胞,而且高铁酸钾氧化水体中MC-LR,通过镜检发现不会造成藻细胞破裂。     

真菌苯二酚内酯聚酮类化合物生物合成研究进展

真菌苯二酚内酯类聚酮化合物具有抗癌和调节免疫系统等重要的生物活性,其生物合成是近年来的研究热点。介绍了苯二酚内酯的双聚酮合酶协作合成机制和组合生物合成,并以几种真菌苯二酚内酯生物合成途径为例,综述了相关的研究进展,以期为研究者提供参考。     

苯二酚内酯合成途径中的聚酮合酶组合表达研究

由真菌聚酮合酶合成的苯二酚内酯类次生代谢产物结构和功能多样,在医药和农业上具有广泛的用途。苯二酚内酯由一对还原型聚酮合酶和非还原型聚酮合酶协同生物催化合成。还原型聚酮合酶和非还原型聚酮合酶由多功能结构域组成,每个结构域在生物合成的过程中程序化地执行特定的功能。通过交换不同真菌苯二酚内酯合成途径中非还原型聚酮合酶的起始物酰基转移酶结构域,在酿酒酵母中与相应的还原型聚酮合酶组合表达,合成了“非天然”的苯二酚内酯聚酮产物,并初步讨论了起始物酰基转移酶结构域的识别规律。     

7种消毒剂对鲟4种病原菌体外抑菌效果

为了筛选高效的消毒剂用于防治鲟细菌性疾病,采用二倍稀释法测定了7种消毒剂对鲟4种病原菌的最小抑菌浓度(MIC)和最小杀菌质量浓度(MBC)。结果显示,高铁酸钾对鲟4种病原菌抑菌效果最好,MIC为8 mg/L,MBC为8¹6 mg/L,戊二醛、甲醛、苯扎溴铵、过氧化氢及季铵盐络合碘5种消毒剂抑菌效果中等,聚维酮碘对鲟4种病原菌抑菌效果最差,聚维酮碘对鲟4种病原菌的MBC最大值为2048 mg/L。根据上述研究结果,选择抑菌效果好的消毒剂高铁酸钾进一步研究了鲟4种病原菌随时间和高铁酸钾浓度变化的生长趋势,显示消毒液浓度为5 mg/L、9 mg/L的消毒液在短时间能抑制病原菌生长繁殖,病原菌数量同样能在短时间内繁殖恢复到原来的水平,浓度为13 mg/L、17 mg/L的高铁酸钾消毒液能快速杀灭病原菌,病原菌在较长时间维持在较低水平,甚至病原菌全部被杀死。研究对于使用高铁酸钾防治鲟养殖实践中的疾病具有重要的指导意义。     

多种农药与次氯酸钠、高锰酸钾和高铁酸钾的反应活性

为探究4类,10种广泛使用的农药(苯氧羧酸类,芳香酸类,取代脲类和烟碱类)与3种氧化剂(次氯酸钠,高锰酸钾和高铁酸钾)的反应活性,本研究在温度(25±2)℃、pH值为8的条件下,分析10种农药分别与3种氧化剂NaClO、KMnO4、K2Fe O4在不同浓度下的反应活性,采用HPLC检测法,对比降解效能,探究氧化剂性质与有机物结构导致的反应活性的差异。实验结果表明,不同种类农药的结构性质对反应活性有重要影响,3种氧化剂的氧化降解能力有明显差异。苯氧羧酸类和芳香酸类农药结构较简单,并含有稳定的苯环或吡啶环结构,氧化降解较困难。取代脲类和烟碱类农药结构较复杂,氧化剂可攻击其不饱和官能团,反应活性较高。NaClO对取代脲类农药的降解率明显优于其他2种氧化剂,3种氧化剂对烟碱类农药的氧化降解效果依次为NaClO>KMn O4>K2Fe O4。研究多种农药与次氯酸钠、高锰酸钾和高铁酸钾的反应活性对降解去除水体中的农药残留对水环境的治理具有重要意义。     

金黄色葡萄球菌对碘伏、乙醇、高铁酸钾和紫外线的抗性

目的了解临床分离的耐甲氧西林金黄色葡萄球菌（methicillin resistant Staphylococcus aureus,MR-SA）、甲氧西林敏感的金黄色葡萄球菌（methicillin sensitive Staphylococcus aureus,MSSA）及金黄色葡萄球菌CMCC（B）26003对碘伏、乙醇医院常用消毒剂及紫外线的抗性。方法以临床连续收集的67株金黄色葡萄球菌为实验菌株。测定碘伏、乙醇、高铁酸钾对耐甲氧西林金黄色葡萄球菌（MRSA）、甲氧西林敏感的金黄色葡萄球菌（MSSA）和金黄色葡萄球菌CMCC（B）26003作用1、2min后的最小抑菌浓度（MBC）及紫外线作用不同时间后的杀菌试验,观察其对碘伏、乙醇、高铁酸钾及紫外线抗性的变化趋势。结果碘伏对MRSA的MBC明显高于MSSA及CMCC（B）26003,而乙醇、高铁酸钾对3种菌的最小抑菌浓度均相近,3种菌对紫外线抗性相近。结论在正常使用浓度范围内碘伏、乙醇、高铁酸钾对金黄色葡萄菌中无论是MRSA、MSSA都有很好的灭菌作用,且乙醇作用时间越长,抑菌效果越显著。紫外线在作用75min以上时,3种菌全部不能存活。     

中华鳖源致病性产吲哚金黄杆菌分离、鉴定及药敏特性分析

对患病中华鳖(Pelodiscus sinensis)进行病原分离、鉴定及药敏实验, 从患病中华鳖皮肤、肝肾脾重要器官分离纯化病原菌, 经理化特性测定及16S rRNA序列分析对其进行鉴定及人工感染试验, 并利用K-B及二倍稀释法进行药敏特性分析。结果表明分离株J22是为中华鳖腐皮病病原, 其对中华鳖的LD₅₀为3.30×104 CFU/g。J22株理化特性与产吲哚金黄杆菌(Chryseobacterium indologenes)一致, 16S rRNA序列与产吲哚金黄杆菌同源性为99%, 综合判定J22株是产吲哚金黄杆菌。分离株对新霉素、庆大霉素及阿莫西林等12种抗生素高度敏感, 对氟苯尼考及多西环素等抗生素耐药; 二氧化氯、漂白粉及高铁酸钾对分离株消毒效果较好。分离菌株J22是中华鳖病原菌, 养殖时可选用庆大霉素、新霉素或者阿莫西林内服, 配合使用二氧化氯、漂白粉及高铁酸钾等外用进行防控。     

苯二酚内酯及其衍生物杀线虫活性研究

采用浸渍法研究了酿酒酵母异源表达的苯二酚内酯monocillin II、10,11-dehydrocurvularin、pre-asperfuranone、trans-resorcylide、desmethyl-lasiodiplodin和lasiodiplodin的杀秀丽线虫活性。首次发现苯二酚内酯10,11-dehydrocurvularin和desmethyl-lasiodiplodin具有杀线虫活性。分别以0.1 mg/m L、0.2 mg/m L和0.5 mg/m L的10,11-dehydrocurvularin和desmethyl-lasiodiplodin处理秀丽线虫的二龄幼虫(L2)24 h后,秀丽线虫的校正死亡率分别为7.95%、15.30%、46.41%和3.41%、8.90%、27.47%。Desmethyl-lasiodiplodin的甲基化产物lasiodiplodin的杀线虫活性降低,浓度为0.5 mg/m L时,线虫的校正死亡率为16.12%。研究结果为植物线虫病害的防治提供了新的思路。     

利用水生植物清除水体中放射性物质的研究 Ⅱ.斜生栅藻对放射性物质的吸收和去除

以斜生栅藻Scenedesmus obliquus (Turp.)Kutz.为材料,进行了藻类对三种放射性物质(K2HPO4-P32,NaI-I131,SrCl-Sr89)的吸收与去除试验。试验结果表明,斜生栅藻对这些放射性物质的吸收能力强,速度快,具有较好的去除效果。用超声波、红外线和γ射线对藻类进行预处理,可以在不同的程度上提高吸收能力和去除效果。       

The reduction of ferrate(VI) to ferrate(V) by ascorbate

The reduction of ferrate(VI) by ascorbate has been studied under anaerobic conditions in the pH range between 6.8 and 11.5 at 24 degrees C. A mechanism is proposed that is consistent with the observed rate constants k11 (HFeO4- + AH-) = (5.6 +/- 0.6) x 10(6) M-1 s-1, k12(FeO4(2-) + AH-) = (1.3 +/- 0.1) x 10(6) M-1 s-1 and the pK(HFeO4- in equilibrium with H(+) + FeO4(2-) = 7.9. Stoichiometric studies show that at high ratios of [AH-]/[FeO4(2-)], one ferrate(VI) oxidizes three molecules of ascorbate to the corresponding ascorbyl (A-) radicals.     

Evaluation of the properties of potassium ferrate used for water purification by luminescence bioassay

Characteristics of four natural water samples from urban and rural areas and the efficiency of a new purifying agent, potassium ferrate K₂FeO₄, were studied by bacterial luminescence bioassay for 30 minutes. It was revealed that two samples of water from the urban areas are toxic, while the other two samples (one from urban and one from rural environment) are nontoxic. Numerous data obtained on the increase in toxicity index with time allow reasonable conclusions to be made about the chemical nature of substances present in the test water samples. Toxic natural water samples were likely to contain heavy metals and were well purified using potassium ferrate, including via their adsorption. In nontoxic natural water samples, toxic complexes with organic compounds present in water could form at the addition of potassium ferrate. The obtained data call for further studying the properties of potassium ferrate complexes with organic compounds. Bacterial luminescence bioassay is a promising method for the rapid assessment of properties of various water sources (their integral toxicity and presumable chemical composition) and new reagents for their purification (effective concentrations, bactericidal properties, and mechanisms of interacting with heavy metals and organic substances in water).     

The Oxidation of Phenol by Ferrate(VI) Andferrate(V). A Pulse Radiolysis and Stopped-Flow Study

Potassium ferrate. K₂FeO₄, is found to oxidize phenol in aqueous solution (5.5 ± pH ± 10) by a process which is second order in both reactants; -d[Fe^vt]/dt=ki[Fe^VI][phenol], kI = 10⁷M^-1s^-1. Product analysis by HPLC showed a mixture of hydroxylated products, principally paraquinone. and biphenols that indicate that oxidation of phenol occurs by both one-electron and two-electron pathways. The two-electron oxidant. producing both para- and ortho-hydroxylated phenols is considered to be ferrate(V) which is itself produced by the initial one-electron reduction of ferrate(VI). The rate of ferrate(V) reaction with phenol was determined by pre-mix stopped flow pulse-radiolysis and found to be k7 = (3.8 ± 0.4)± 10⁵M^-1s^-1.     

Catalytic and immunochemical properties of arylsulphatase A from urine, modified by potassium ferrate

Arylsulphatase A (EC 3.1.6.1.) from urine was inactivated with potassium ferrate, a strong oxidizing agent. The inhibition could be prevented by competitive inhibitors, tetraborate and orthophosphate. Tetraborate which was shown to be a powerful competitive inhibitor (determined Ki = 4 X 10(-5) M) gave more efficient protection. The partially inactivated enzyme exhibited a Km value similar to that of the unmodified arylsulphatase A, and its Vmax decreased in proportion to the loss of enzymatic activity. The partially modified enzyme did not lose its ability to catalyse hydrolysis of p-nitrocatechol sulphate according to the "anomalous kinetics" exhibited towards this substrate and characteristic for arylsulphatase A. The immunochemical properties of arylsulphatase A either fully or partially inactivated were similar to those of the native enzyme. The results allow to conclude that ferrate reacts with arylsulphatase A in its active site. Thus ferrate seems to be a very sensitive probe for amino acid residues essential for catalytic activity of arylsulphatase A.     

Ferrate oxidation of Escherichia coli DNA polymerase-I. Identification of a methionine residue that is essential for DNA binding

Treatment of Escherichia coli DNA polymerase-I with potassium ferrate (K2FeO4), a site-specific oxidizing agent for the phosphate group-binding sites of proteins, results in the irreversible inactivation of enzyme activity as judged by the loss of polymerization as well as 3'-5' exonuclease activity. A significant protection from ferrate-mediated inactivation is observed in the presence of DNA but not by substrate deoxynucleoside triphosphates. Furthermore, ferrate-treated enzyme also exhibits loss of template-primer binding activity, whereas its ability to bind substrate triphosphates is unaffected. In addition, comparative high pressure liquid chromatography tryptic peptide maps obtained before and after ferrate oxidation demonstrated that only five peptides of the more than 60 peptide peaks present in the tryptic digest underwent a major change in either peak position or intensity as a result of ferrate treatment. Amino acid analyses and/or sequencing identified four of these affected peaks as corresponding to peptides that span residues 324-340, 437-455, 456-464, and 512-518, respectively. However, only the last peptide, which has the sequence: Met-Trp-Pro-Asp-Leu-Gln-Lys, was significantly protected in the presence of DNA. This latter peptide was also the only peptide whose degree of oxidation correlated directly with the extent of inactivation of the enzyme. Amino acid analysis indicated that methionine 512 is the target site in this peptide for ferrate oxidation. Methionine 512, therefore, appears to be essential for the DNA-binding function of DNA polymerase-I from E. coli.     

Enhancing and inhibiting effects of benzenediols on chemiluminescence of a novel cyclometallated iridium(III) complex

A novel chemiluminescence (CL) system, including the cyclometallated iridium(III) complex {tris[1‐(2,6‐dimethylphenoxy)‐4‐(4‐chlorophenyl)phthalazine]iridium}, potassium permanganate and oxalic acid, is proposed for the determination of benzenediols. This method is based on the fact that hydroquinone and catechol exhibited an inhibiting effect, while resorcinol exhibited an enhancing effect on CL intensity. The optimum conditions for CL emission were investigated. Under optimal conditions, the detection limits of hydroquinone, catechol and resorcinol were 6.4 × 10^?8, 2.7 × 10^?9 and 8.1 × 10^?7 mol/L, respectively. The method has been successfully applied to the determination of benzenediols in different types of water sample. The luminophors of the CL systems were all identified as the metal–ligand charge‐transfer (MLCT) excited state of the iridium complex. Copyright © 2011 John Wiley & Sons, Ltd.     

Inactivation of phosphorylase b by potassium ferrate, a new reactive analogue of the phosphate group.

Rabbit muscle phosphorylase b reacts with the phosphate-like reagent potassium ferrate, K2FeO4, a potent oxidizing agent. The reaction results in inactivation of the enzyme and abolition of the ability of the enzyme to bind 5'-AMP. Activating and nonactivating nucleotides which bind at the 5'-AMP binding site such as 5'-AMP, 2'-AMP, 3'-AMP, and 5'-IMP substantially protect the enzyme from inactivation by ferrate. One to two residues of tyrosine and approximately 1 residue of cysteine are modified by ferrate under the conditions employed. Tyrosine is protected by 5-AMP, whereas cysteine is not. The tyrosine modification is suggested as the inactivating chemical reaction. The location of the inactivating reaction is suggested to be in or near the 5'-AMP binding site. The structural and chemical properties of ferrate ion are discussed and compared to those of phosphate. Ferrate ion may be a reagent useful for phosphate group binding site-directed modification of proteins.