Effect Of Syringa Leaves Extract Inhibiting Biofilm Formation By Streptococcus Suis And Succinic Acid Affecting Cps Genes Expression

Bacterial biofilm(BF) refers to bacteria cluster as a single or multiple kinds of bacteria in order to adapt to the surrounding environment, which adhered to an inert surface or to a tissue, colonization and secretion of polysaccharide matrix, fibrous protein, lipoprotein, causing bacteria adhesion, aggregation and formation of three-dimensional structures. Biofilm bacteria is a kind of state different from planktonic bacteria, once bacteria biofilm is formed, its resistance to antibiotics can improve 10 ~ 1000 times and thereby limits therapeutic options.Streptococcus suis(S.suis), particularly serotype Ⅱ,which is an important zoonotic agent in both pigs and humans, causing purulent meningitis, septicemia, endocarditis pneumonia and arthritis, etc. It is difficult to eradicate after formation, causing infection in delay. Therefore, how to inhibit BF production and reduce the infection of BF becoming the focus of domestic and foreign scientific research workers is a veterinary clinical problem to be solved.Folium syringae leaves and different parts of it and succinic acid were screened by means of the colony forming unit method, crystal violet staining and scanning electron microscopy. After then another research that streptococcus suis biofilm cps sequencing of gene cluster were effected by succinic acid.Current research has shown that 1/2 MIC(6.25mg?m L-1) concentration of Folium syringae leaves and 1/2 MIC(3.125mg?mL-1) concentration of Ethyl acetate extraction from Folium syringae leaves and 1/2 MIC(3.125mg?mL-1) concentration of N-butyl alcohol extraction from Folium syringae leaves can reduce the generation of biofilm. By scanning electron microscope we find that the S.suis biofilm structure before and after the intervention are very different. the previous increased with the increase of drug concentration in the dense structure gradually disappear. Gene sequencing results show that the cps2 B nucleotide changes to A�'T, the corresponding amino acid change for K�'I, the cps2 E nucleotide changes to A�'T, the corresponding amino acid change for V�'D, the cps2 L nucleotide changes to A�'C, the corresponding amino acid change for T�'A. By predicting cps2 B cps2E and cps2 L secondary structure,we find that they are different after the succinic acid intervention. The results are likely to affect the CPS protein, further influence the production of BF.In conclusion, Folium syringae leaves, both of N-butyl alcohol and N-butyl alcohol extraction from Folium syringae leaves and succinic acid reduce the generation of biofilm in a dose dependent manner, effectively inhibit S.suis biofilm formation.The succinic acid can change the nucleotide of cps2B、cps2E and cps2 L, the corresponding amino acid also change because of the changes. The secondary structure of experimental group are different from the control group.