Abstract: In order to screen the probiotic which can inhibit the formation of Fusobacterium nucleatum biofilm under oral neutral pH, F. nucleatum was treated with pH 6.6 cell-free supernatant (CFS) from different probiotics, and its biofilm was determined by crystal violet semi-quantitative method.Lactobacillus plantarum UD01 was selected, due to its CFS(pH 6.6) could reduce the F. nucleatum biofilm.The minimum biofilm inhibition concentration (MBIC) was determined by the micro-dilution method, and the MBIC was 250 μL/mL. The results of SEM and CLSM showed that F.nucleatum biofilm decreased and became thinner, besides, its structure was looser after treated with UD01 CFS(pH 6.6). Growth curve, qPCR of adhesion-associated outer membrane protein genes, and extracellular polymeric substances (EPSs) experiments indicated that UD01 CFS (pH 6.6) could not inhibit the growth of F. nucleatum, and its possible action mechanism against F. nucleatum biofilm was to down-regulating the expression of adhesion-associated outer membrane protein genes, reduced the secretion of extracellular protein and polysaccharide, thereby reduced the adhesion ability of F. nucleatum, and ultimately inhibited F.nucleatum biofilm.

Key words: halitosis, Fusobacterium nucleatum, probiotics, biofilm, adhesion ability