Expression Of AiiA In E.coli And Its Activity Bioassay

Bacteria utilize signals molecules or autoinducer(AIs) as language to communicate.They continue secreting signals molecules outside the cells as growing,and detect the concentration change. When the concentration reach threshold, the AHL molecule diffuses into the cell and binds to its cognate receptor, which in turn activates or represses the coordinated expression of particular sets of genes that enhance the ecological competence of the bacterium . This density-dependent manner, is referred to as quorum sensing. To many pathogens, quorum sensing plays a great role in their pathogenicity.Soft rot desease is a kind of bacreria desease which occurs throughout the country, E. carotovora is a phytopathogen that causes soft rot in a variety of plants. The pathogenicity of E. carotovora depends on the production of various plant tissue-degrading enzymes, including pectate lyases, polygalacturonase, cellulase, and proteases. These enzymes are involved in maceration of plant tissue necessary for bacterial colonization of the host. Production of enzymes by only a few cells of E. carotovora would not have an effect on the plant tissue, and more likely, it would activate the plant phytodefense mechanisms. Therefore, E. carotovora uses quorum sensing, which ensures that exoenzyme production does not occur until sufficient bacterial numbers have been achieved for successful tissue destruction and evasion of plant defenses. A gene encoding autoinducer inactivation (aiiA) has been cloned from the Gram positive bacterium Bacillus sp. 240B1. The aiiA gene product degrade AHLs so that inhibits virulence of E. carotovora.Our expriment based on the reported aiiA gene and designed two primers. AiiA gene was cloned from Bacillus thuringiensis before transplanted to expression vetor pQE-30,...