PNS (Panax notoginseng saponins) is the main medical bioactive component in Panax notoginseng. The medical value of PNS cannot be extended because of its low production. With the deep study of saponins biosynthetic pathway, the control of PNS biosynthesis through metabolic engineering has gradually become possible. In this study, the Squalene synthase (SS) over-expression vector was established. By the way of agrobacterium-mediated method, the vector was transfered and integrated into the Panax notoginseng genome. The result of the PCR detection and the saponin content detection shows that over-expression SS is able to produce high level of Panax notoginseng saponins, and confirms the regulatory function of SS in the biosynthesis of ginsenosides in Panax notoginseng. It provides a theoretical basis and technical basis for the construction of PNS homologous or heterologous efficient expression system in the future.

In order to know that Streptococcus exist in health swine herd,2 204 cases of nose swabs were collected in swine from different areas in Dongbei three province of northeast China.Seed swab to Streptococcus culture medium,24 hours after culturing,gram staining with becteria culture,gram positive Streptococcus were identified with PCR technology,then farther identified serotype with Streptococcus suis 1,2,7,9 serotype special primers.The results showed that Streptococcus exist rate in swine herd of Heilongjiang,Jinlin,Liaoning is 29 %,27 %,34 %,respectively.PCR typing assay indicated that 155 strains of Streptococcus suis were isolated including 7 strains of 1 serotype,39 strains of 2 serotype,4 strains of 7 serotype,11 strains of 9 serotype,94 strains of other serotype in three province of northeast China.