一株炭样小单孢菌产新型核苷类抗生素的抗菌作用研究

发布时间：2018-06-07 17:44

本文选题：炭样小单孢菌 + 核苷类抗生素　；参考：《江西师范大学》2013年硕士论文

【摘要】：新抗生素产生菌的分离、筛选是研发新抗生素的重要途径之一，，课题组前期研究获得的炭样小单孢菌所产抗菌单体组分经鉴定为一新型核苷类抗生素。该抗生素具有广谱抗菌活性，但抗菌作用特点及作用机理不清楚。本研究以该抗生素和常用抗生素活性检测靶菌分别作为试验材料和试验对象，研究抗生素的体外抗菌谱、抗菌方式、抗菌强度及其作用机理，为进一步开发炭样小单孢菌产抗生素成为我国具有自主知识产权的新型抗生素奠定坚实的理论基础，具有重大的理论研究和实践应用价值。研究结果如下：（1）采用琼脂扩散法和液体稀释法分别测定了炭样小单孢菌所产核苷类抗生素抗菌谱及其最低抑菌浓度和最低杀菌强度，表明该抗生素对常见的G+和G-均具有抗菌作用，为广谱抗生素，并且对G+和G-的最低杀菌浓度（MBC）一般是最低抑菌浓度（MIC）的8～16倍。（2）采用显微观察法研究了炭样小单孢菌所产核苷类抗生素处理后的G+和G-细菌形态变化，结果显示，在最低抑菌浓度的抗生素作用下，无论是G+、G-，细胞形态都发生明显改变，许多细胞形体变长，甚至成丝状，还有部分细胞开始破裂，并且，细胞的个体数目明显减少。（3）通过比较抗生素处理前后细胞对溶菌酶的敏感性及细胞壁的含量，表明炭样小单孢菌所产核苷类抗生素的作用不影响细菌细胞壁的合成，但使细胞壁变厚。（4）通过比较抗生素作用后细胞悬浮液的电导率变化，表明抗生素对细菌细胞膜的渗透性没有明显的影响，说明不影响细胞膜的结构与功能。（5）采用孔雀石绿—磷钼杂多酸分光光度法测定了抗生素对细胞GTP酶活性的影响，表明炭样小单孢菌所产抗生素可促进细胞GTP酶的活性，进而增强了GTP酶的催化作用。（6）采用G-250考马斯亮蓝法检测了炭样小单孢菌所产抗生素作用下G+和G-细菌细胞内蛋白质含量的变化，及其对大肠埃希氏菌无细胞表达系统体外合成蛋白质的影响，表明炭样小单孢菌所产抗生素可抑制细胞蛋白质的合成。从上述结果可以推断，炭样小单孢菌所产抗生素通过抑制细胞蛋白质的合成而抑制细胞的分裂，进而实现其抑/杀菌功能。但有关该抗生素抑制蛋白质合成的具体机制还有待进一步研究。
[Abstract]:Isolation and screening of new antibiotic producing bacteria is one of the important ways to develop new antibiotics. The antibiotic has broad-spectrum antibacterial activity, but its characteristics and mechanism are not clear. In this study, the antimicrobial spectrum, antimicrobial method, antibacterial intensity and its mechanism of antibiotics were studied by using the antibiotic and the commonly used antibiotic activity detection target bacteria as the test materials and experimental objects, respectively. It lays a solid theoretical foundation for the further development of carbon-like micromonosporium antibiotics as a new type of antibiotics with independent intellectual property rights in China, and has great theoretical research and practical application value. The results are as follows: 1) the antimicrobial spectrum of nucleosides produced by Micromonosporium carboniformis and its minimum inhibitory concentration and bactericidal intensity were determined by Agar diffusion method and liquid dilution method respectively. The results showed that the antibiotic had antimicrobial effect on both G and G-, and it was a broad-spectrum antibiotic. And the minimum bactericidal concentration (MBC) of G and G- was 816 times of the minimum inhibitory concentration (MICM). The morphological changes of G and G- bacteria were studied by microscopic observation after treatment with nucleoside antibiotics produced by Micromonospora. In the presence of antibiotics with the lowest inhibitory concentration, the morphology of the cells, no matter the G G, changed significantly, many of the cells became longer, even became filamentous, and some of the cells began to break down, and, By comparing the sensitivity of cells to lysozyme and cell wall content before and after antibiotic treatment, the results showed that the effect of nucleoside antibiotics produced by Micromonosporium carboniformis did not affect the synthesis of bacterial cell wall. But the thickening of the cell wall showed that antibiotics had no obvious effect on the permeability of bacterial cell membrane by comparing the changes of the electrical conductivity of the cell suspensions after the treatment of antibiotics. The results showed that the structure and function of cell membrane were not affected. (5) the effect of antibiotics on the activity of GTP enzyme was determined by malachite green-molybdenum heteropoly acid spectrophotometry, which indicated that the antibiotics produced by Micromonosporium Carboniformis could promote the activity of GTP enzyme. Furthermore, the catalytic activity of GTP enzyme was enhanced. (6) G-250 Coomassie brilliant blue method was used to detect the changes of protein contents in G and G- bacteria cells under the action of antibiotics produced by Micromonosporium carboniformis. And its effect on the protein synthesis of Escherichia coli acellular expression system in vitro, indicating that antibiotics produced by Micromonosporium carboniformis can inhibit the synthesis of cellular protein. The antibiotics produced by Micromonosporium carboniformis inhibit cell division by inhibiting the synthesis of cell proteins and thus achieve its inhibitory / bactericidal function. However, the mechanism of inhibition of protein synthesis by this antibiotic remains to be further studied.
【学位授予单位】：江西师范大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：S482.28

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