Effect Of Oleic Acid On The Formation Of Porphyromonas Gingivalis Biofilm

ObjectiveTo explore the antibacterial and antibiofilm activities of oleid acid(OA)against two strains of Porphyromonas gingivalis(P.gingivalis).Methods1.Two strains of P.gingivalis,W83 and ATCC33277 were enriched in the Brain Heart Infusion(BHI)Liquid Medium.A certain concentration of the bacterial liquid in exponential growth phase was selected to be cultured in the BHI liquid medium with or without oleic acid for 24 hours.Crystal violet staining was used to detect and quantify biofilms to determine the optimal concentration of bacterial biofilms and the 50%inhibitory concentration(IC50)of oleic acid on biofilms of two strains.2.The effects of oleic acid on bacteria and biofilm were observed by adding IC50 concentration of oleic acid at different time and incubating for 24 hours.3.The morphological changes of bacteria caused by oleic acid were evaluated by scanning electron microscopy(SEM)after treatment with IC50oleic acid and compared with untreated bacterial samples.4.Real-time PCR was used to detect the effect of IC50 concentration of oleic acid on the expression of virulence-related genes in two strains.Results1.The optimum concentration of P.gingivalis for biofilm formation was 1×10~8/mL.The IC50 of OA for P.gingivalis W83 is 1.55nM,and that of OA for P.gingivalis ATCC33277 is 1.76nM.2.When the biofilm formed stably,the adherent bacterial population was treated with OA increased following with the increase of the level of OA(P<0.05).On the contrary,the planktonic bacteria decreased in proportion to the level of OA(P<0.05).When OA was co-cultured with bacteria in the initial stage and the concentration was higher than 8 x IC50,OA significantly inhibited the formation of biofilm and the number of planktonic bacteria(P<0.05).ConclusionsOA has strong anti-bacterial and anti-biofilm effects on P.gingivalis.The inhibition of OA on biofilm is achieved in the initial stage.