Abstract: Objective: To study the effects of streptococcus sanguis bacteriocins on the surface morphology and the mechanical properties of porphyromonas gingivalis (P.g). Methods: Standard strains ATCC10556 and ATCC33277 were recovered and extended. Streptococcus sanguis bacteriocins was extracted by low temperature high-speed centrifugation and ultrasonic broken. Streptococcus sanguis bacteriocins was affected with P.g at 37℃ and anaerobic cultured for 48h. Atomic force microscope (AFM) was used to observe the microstructure of Streptococcus sanguis bacteriocins on P.g. Through the force-distance curve, the Young's modulus and adhesion of Streptococcus sanguis bacteriocins on P.g were calculated. Results: AFM showed that Streptococcus sanguis bacteriocins could reduce the diameter of P.g, rise the average roughness and average peak height (P<0.05). After Streptococcus sanguis bacteriocins on P.g, the adhesion and the Young's modulus of P.g reduced significantly (P<0.001). The adhesion and the Young's modulus of P.g were (0.7±0.1)nN and (5.54±0.16)Mpa. After Streptococcus sanguis bacteriocins on P.g, the adhesion and the Young's modulus of P.g were 0.50± 0.1nN and 3.97±0.64Mpa. Conclusion: Streptococcus sanguis bacteriocins can change the morphology of P.g and reduce the adhesion and the Young's modulus of P.g.

Key words: Streptococcus sanguis bacteriocins , Porphyromonas gingivalis Atomic force microscope (AFM) , Morphology , Mechanical properties