Gene Cloning Of Quorum Quenching Enzyme And Enzymatic Property

Quorum sensing(QS) is a phenomenon that bacterial cells interact each other through signal molecules. Bacterial cells secrete and respond to specific signal molecules. When the signal molecule concentration reaches a certain density value, bacterial cells will start the expression of specific genes, especially many pathogenic genes. Thus, it provides a new thought for the prevention and treatment of certain plant and animal pathogenicity disease. Quorum quenching(QQ) is a sort of prevent and control method for these disease based on QS, it can reduce the signal molecule concentrations under the threshold value through degradate the signal molecules produced by bacteria cells and makes the bacteria incapable to express the certain pathogenic factor. To date, a number of genes that express QQ enzyme have been found. In order to seek new QQ enzyme genes, 7 bacterial strains purchased from DSMZ were activatied and QQ activity was screened in which 6 strains presented the QQ activity and the strain DSM16502 with the highest QQ activity was selected. This strain was identified as Alcanivorax dieselolei. Then, genomic library of DSM16502 was consducted by shotgun to screen the gene that express QQ enzyme. The genomic library contained 11646 monoclonals. But the target gene expressing the QQ enzyme couldn`t be obtained after screening the library. Ammonium sulfate precipitation showed that the QQ enzyme produced by strain DSM16502 could be precipitated in 50% saturation of ammonium sulfate solution. The properties of QQ enzyme produced by DSM16502 were investigated. It was found that the enzyme activity was lost within pH1- 4 and remained within pH5-13. Metal ions including Li+, Ni+, Ca2+, Mg2+, Zn2+, Mn2+, Cu2+, Fe2+ and Co2+ did not significantly affect enzyme activity. Its optimum reaction temperature beween 30℃and 40 ℃.It can remain partial quenching activity even in 70 ℃å'Œ 80 ℃,indicate its application prospect.