汞对固定化斜生栅藻净化污水及其生理特征的影响

研究了在不同Ｈｇ浓度条件下,固定化斜生栅藻对污水中氨氮、正磷酸盐和Ｈｇ的净化效率及其生理特征变化,结果表明,固定藻的净化效率和对Ｈｇ毒性的抗性明显高于悬浮藻。０．２ｍｇ．Ｌ＾－１Ｈｇ对固定藻的净化效率无影响,并对ＰＯ＾３－４－Ｐ的吸收有刺激促进作用,而悬浮藻的开始下降;从０．８－１．４ｍｇ．Ｌ＾－１,随着Ｈｇ浓度的增加,固定藻对氨氮和正磷酸盐的净化效率逐渐下降,而悬浮藻的则急剧下降,固定藻对汞的去     

Diversity of mercury resistance plasmids obtained by exogenous isolation from the bacteria of sugar beet in three successive years

Abstract: Self-transmissible plasmids conferring mercury resistance were exogenously isolated from the bacterial populations of sugar beet roots (rhizoplane) and leaves (phyllosphere) into a Pseudomonas putida recipient. Fifty rhizoplane plasmids and 29 phyllosphere plasmids (60–383 kb) were purified. Numerical analysis of plasmid DNA restriction enzyme digest patterns identified five distinct groups. Three of these plasmid groups were isolated from sugar beet crops grown at the same site over three consecutive years, demonstrating their established presence. Each group of plasmids comprised individual isolates with structural additions or deletions. The frequency of exogenous isolation correlated with factors likely to influence plant growth, bacterial activity and the physiological state of donors prior to sampling. All plasmids investigated conferred narrow spectrum mercury resistance with a reductase detoxification mechanism. None of the plasmids conferred resistance to a range of antibiotics, other heavy metals, or to UV, and following transfer to recipient bacteria the range of carbon source utilisation was not altered. This is the first report of the persistence of Pseudomonas spp. plasmid structural types isolated over several years from a terrestrial habitat.     

Overexpression of MerT, the mercuric ion transport protein of transposon Tn501, and genetic selection of mercury hypersensitivity mutations

The small (116 amino acids) inner membrane protein MerT encoded by the transposon Tn501 has been overexpressed under the control of the bacteriophage T7 expression system. Random mutants of MerT were made and screened for loss of mercuric ion hypersensitivity. Several mutantmerT genes were selected and sequenced: Cys24Arg and Cys25Tyr mutations abolish mercury resistance, as do charge-substitution mutations in the first predicted transmembrane helix (Glyl4Arg, Glyl5Arg, Gly27Arg, Ala18Asp), and the termination mutations Trp66Ter and Cys82Ter.     

一株高抗汞细菌的分离鉴定及其抗性基因的克隆与表达

摘要：【目的】本研究旨在从重金属汞抗性细菌中分离鉴定汞抗性基因【方法】从北京凉水河河床底泥中分离抗汞细菌,采用16S rRNA基因序列分析结合生理生化特征对菌株进行鉴定。根据GenBank中已发表的多种抗汞细菌的merA基因序列设计引物,以抗性细菌基因组DNA为模板,扩增merA基因,并在大肠杆菌（Escherichia coli）BL21(DE3)表达。同时对表达菌株的重金属汞抗性进行测定。【结果】分离得到一株能在含HgCl2为70 mg/L的平板上生长良好的高抗汞细菌,编号为KHg2。16S rRNA     

Plasmid-encoded mercury resistance in a Pseudomonas stutzeri strain that degrades o-xylene

Abstract A Pseudomonas stutzeri strain, previously isolated for its ability to utilize o -xylene, bears a plasmid, pPB, of about 80 kbp. pPB was found to encode resistance to mercuric chloride and organomercury compounds. Loss of the plasmid resulted in a simultaneous loss of the metal resistance, but not of the ability to degrade o -xylene. Transfer of the Hg^r phenotype to an Hg^s strain was achieved by mobilizing pPB with RP4. Mercury reductase activity was induced by mercuric chloride and by phenylmercuric acetate and Thimerosal. pPB may be considered a broad spectrum resistance plasmid.     

类胡萝卜素合成的相关基因及其基因工程

类胡萝卜素具有多种生物功能,尤其在保护人类健康方面起着重要的作用,如它们是合成维生素A的前体,能够增强人体免疫力和具有防癌抗癌的功效。人体自身不能合成类胡萝卜素,必须通过外界摄入;但类胡萝卜素在许多植物中含量较低,并且很难用化学方法合成。随着类胡萝卜素生物合成途径的阐明及其相关基因的克隆,运用基因工程手段调控类胡萝卜素的生物合成已成为可能。本文综述了微生物和高等植物类胡萝卜素生物合成途径中相关基因的克隆,以及运用这些基因通过异源微生物生产类胡萝卜素和提高作物类胡萝卜素含量的基因工程研究进展。     

高通量测序在病原微生物耐药方面的应用进展

高通量测序是一种高效、准确、价廉的新型测序技术,随着近年来的不断推广,逐渐进入不同的研究领域。目前,多重耐药菌的感染给患者和社会增加了巨大负担,耐药机制和抗菌药物的研发是科学研究的热点之一。高通量测序技术也开始在病原微生物耐药方面发挥了巨大作用,尤其是在耐药机制研究方面,解决了一些用现有的技术无法解决的问题。本文从病原菌鉴定、耐药机制、药物新靶标、耐药菌流行病学以及用药指导等方面阐述了高通量测序在病原微生物耐药方面的应用及进展,重点讨论了耐药机制和抗菌药物新靶标进展以及现阶段存在的问题。高通量测序技术不断发展,尤其是进入病原微生物研究领域后延伸出新的研究技术和方法,随着相关的生物信息学的进步,此项技术应用将会更加广泛。     

Effect of salinity on the adaptive capacity of recombinant strains ofEscherichia coli andBacillus subtilis

The effect of different concentrations of salts on natural and recombinant strains ofBacillus subtilis andEscherichia coli was studied. The recombinant strain ofB. subtilis was found to be more osmotolerant than the wild-type strain of this bacterium, whereas the opposite situation was observed for the recombinant and wild-type strains ofE. coli. Some salts exerted a bacteriostatic effect onE. coli andB. subtilis. The adaptive capacity of recombinant strains depended on the number of plasmid copies in the cells. The introduction of recombinant bacteria into model ecosystems resulted in the generation of their variants with increased osmotolerance.     

微生物对偶氮染料的脱色及其基因工程研究进展

偶氮染料广泛应用在纺织印染、造纸印刷等行业中。染料废水的排放将会导致严重的环境污染,使用微生物处理染料废水是解决此问题的有效方法。该文概述了微生物对偶氮染料的脱色的研究,包括细菌对偶氮染料的脱色,真菌对偶氮染料的脱色,脱色产生的芳香胺并进一步被降解,以及基因工程技术在微生物对偶氮染料脱色的研究进展。     

植物防御系统中抗病相关基因的研究进展

本文论述了植物防御系统中抗病相关基因（resistance gene,R基因）的研究进展。列表总结了迄今已克隆的R基因,并将其归为四种不同的类型。综述了不同基因表达产物-R蛋白在细胞中的定位及其相应的功能。此外,还对R基因编码区的多态性、R基因在染色体上排列方式以及R基因的进化与起源等问题进行了讨论。Abstract:This review comments on recent advances in research of disease resistance genes(R Genes) in defence system of plants.The R genes cloned up to date are summarized and classified roughly into four classes listed in the Table 1.The location and the founction of the R proteins,i.e.,the expressed products of different R genes in the cells are reviewed.In addition,the polymophism of coding region of R genes,the different fashions of R gene arrangement on the chromosomes,and the evolution and origin of R genes are discussed.     

北京东灵山树线处土壤细菌的PICRUSt基因预测分析

树线变动会对生物多样性分布以及生态系统功能的维持造成深远影响,研究树线处土壤微生物群落及其功能,对预测高海拔生态系统响应气候变化具有重要价值。采用Mi Seq高通量测序技术及PICRUSt基因预测分析方法,对北京东灵山辽东栎林及树线之上亚高山草甸的土壤细菌群落及功能进行对比研究,结果表明:土壤细菌物种多样性在树线处没有发生显著的变化,沿海拔也没有呈现出明显趋势,但细菌群落结构以及预测功能基因均发生了变化。在39个二级预测功能分类中有10个子功能的相对多度在森林和草甸中具有明显差异。其中,其他次生产物代谢的生物合成、转录、多糖生物合成和代谢、酶家族、信号分子及交互作用、环境适应、细胞生长和死亡等的功能基因在森林中明显高于草甸中;而维他命及辅因子代谢、膜运输、内分泌系统等的功能基因在草甸中偏高。