The Construction and Application of Biosensor for Detection of Quorum Sensing in Pseudomonas Aeruginosa and Serratia Marcescens

作     者：Truong Ngoc Tu张玉秀 

作者单位：华东理工大学 

学位级别：硕士

导师姓名：沈亚领

授予年度：2011年

学科分类：0710[理学-生物学] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 071005[理学-微生物学] 10[医学] 

主      题：生物传感器 铜绿假单胞菌 革兰氏阴性细菌 

摘      要：Quorum sensing （QS） is a phenomenon present in many gram-negative bacteria that allows bacterial communication and controlled expression of a large suite of genes through quorum sensing signals-N-acyl homoserin lactones （AHLs）. Generally, QS can occur between diverse species as well as within a single bacterial species, and can control a host of different processes, essentially serving as a simple communication network. A variety of different molecules can be used as signals. Common classes of signaling molecules are oligopeptides in gram-positive, AHL in gram-negative bacteria and a family of autoinducers known as autoinducers-2 in both gram-negative and gram-positive bacteria. Bacteria that use quorum sensing constantly produce and secrete certain signaling molecules-autoinducers or pheromones. These bacteria also have a receptor that can specifically detect the signaling molecule （called inducer）. When the inducer binds the receptor, it activates transcription of certain genes, including those for inducer synthesis. There is a low likelihood of a bacterium detecting its own secreted inducer. Thus, in order for gene transcription to be activated, the cell must encounter signaling molecules secreted by other cells in its environment. When only a few other bacteria of the same kind are in the vicinity, diffusion reduces the concentration of the inducer in the surrounding medium to almost zero, so the bacteria produce little inducer. However, as the population grows the concentration of the inducer passes a threshold, causing more inducer to be synthesized. This forms a positive feedback loop, and the receptor becomes fully activated. Activation of the receptor induces the up regulation of other specific genes, causing all of the cells to begin transcription at approximately the same time. This coordinated behavior of bacterial cells can be useful in a variety of situations. In this study, in order to investigate quorum sensing in Pseudomonas aeruginosa and S