铜绿假单胞菌（pseudomonas aeruginosa）致病因子受低于最小抑制浓度抗生素调节的研究

发布时间：2018-03-22 00:12

本文选题：铜绿假单胞菌　切入点：转座突变　出处：《西北大学》2006年硕士论文　论文类型：学位论文

【摘要】：铜绿假单胞菌是(Pseudomonas aeruginosa)一种机会致病菌,它可以在人群中引起严重的急性和慢性感染,是病人在医院期间发生感染的第三大致病菌。许多抗生素对其具有一定的治疗作用,但铜绿假单胞菌有一个重要特性是它对许多抗生素具有很高的内在抗药性。因此开发新的抗生素是控制铜绿假单胞菌感染的有效途径。抗生素作为微生物分泌出来的一种化学物,它除传统的杀菌或抑菌外,还表现出了其他的一些活性。在低于最小抑制浓度条件下,它作为一种化学信号对许多基因的表达起着重要的调节作用。研究低于最小抑制浓度抗生素将有助于我们更好的了解病原菌的致病性和耐药性,从而找到细菌对抗生素的耐药靶点。在本实验中,通过构建的启动子-lux报道子为载体,研究了低于最小抑制浓度的抗生素对铜绿假单胞菌中的一些致病因子基因表达的影响,结果表明:1.低于最小抑制浓度的抗生素(1/4和1/8 MIC)的四环素对所构建的31个基因中的一部分表达具有明显的调节作用,在所研究的31个基因中,受到激活作用的有21个,与对照相比,表达量变化最高的超过10倍。2.为了了解基因表达受抗生素调节的部分途径,我们通过转座突变的方法,以受四环素(Tetracycline)调节的吩嗪合成基因pKD-phzAl为研究对象,找到了30个负调节基因,这些基因能使四环素对pKD-phzAl的调节程度降低;20个正调节基因,它们促使四环素对pKD-phzA1的调节程度提高,其最大程度达到20倍;3.在所选取的两个突变体中,确定这两个突变基因是通过细菌群体感应(quorum-sensing)而影响四环素对pKD-phzAl表达水平的调节,从而可以了解该基因对pKD-phzAl表达的调节途径;
[Abstract]:Pseudomonas aeruginosa, a opportunistic pathogen, can cause severe acute and chronic infections in the population, and is the third leading cause of infection in hospital. Many antibiotics have a certain therapeutic effect on it. However, an important characteristic of Pseudomonas aeruginosa is its high intrinsic resistance to many antibiotics. Therefore, the development of new antibiotics is an effective way to control the infection of Pseudomonas aeruginosa. Antibiotics, as a chemical secreted by microbes, exhibit some other activities in addition to traditional bactericidal or bacteriostatic activities. As a chemical signal, it plays an important role in regulating the expression of many genes. The study of antibiotics below the minimum inhibitory concentration will help us to better understand the pathogenicity and drug resistance of pathogenic bacteria. In this study, the expression of some pathogenic factors in Pseudomonas aeruginosa was studied by using the promoter lux reporter as the vector, and the effect of antibiotics below the minimum inhibitory concentration on the gene expression of some pathogenic factors in Pseudomonas aeruginosa. The results showed that tetracycline (1 / 4 and 1 / 8 MICM) below the minimum inhibitory concentration significantly regulated the expression of some of the 31 genes constructed. Of the 31 genes studied, 21 were activated. In order to understand some pathways of gene expression regulated by antibiotics, the phenazine synthetic gene pKD-phzAl regulated by Tetracycline (Tetracycline) was studied by transposition mutation. Thirty negative regulatory genes were identified, which reduced the regulatory degree of tetracycline to pKD-phzAl, and 20 positive regulatory genes, which increased the regulatory degree of tetracycline to pKD-phzA1 with a maximum of 20 times. It is confirmed that these two mutant genes affect the regulation of tetracycline on the expression of pKD-phzAl by means of bacterial population induction quorum-sensing, so as to understand the regulatory pathway of the gene to the expression of pKD-phzAl.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2006
【分类号】：R378

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