The Antibacterial Effects Of Lactoperoxidase System On Porphyromonas Gingivalis And Fusobacterium Nucleatum

The lactoperoxidase system consist of lactoperoxidase, halides ( Cl^-, I^-, SCN^- ) and H₂O₂. The oxidation product of I^- has a greater antibacterial effect to most Gram negative bacterial than that of SCN^- , but this effect can be diminished by the presence of physiological concentration of SCN^- which can always be found in human saliva. Thus, there might be a way to enhance the antibacterial effects of LP^- SCN^- -I^- through addition of I^- to overcome the present of SCN^-.Objective: to investigate the antibacterial effect, metabolism, pathogenesis and morphology changes of LP-I-H₂O₂ system with physiological concentration of SCN^- on Pg and Fn.Methods: the standard strain of Pg and Fn were cultivated in Brain Heart Infusion agar plate and the colonial forming units (CFU)were enumerated. ATP and TLP were examined through specific kits. Morphological changes were examined through electronic scanning microscope.Results: 1.(1) The antibacterial effects of LP- I" system with physiological concentration of SCN" on Pg and Fn in buffer solution for 30min was significantly higher than that of LP-SCN" system alone when I" concentration was over 500uM (P<0.05) but lower than the I"5000uM group (P<0.05). (2) When compare buffer to saliva, the former condition was more positive for the antibacterial effects of LP system under the same circumstances, but still work on the latter condition. logCFU/ml of Pg was 3.land 5.4 respectively while on Fn it is 3.0and 5.6. (3) The overall trend in ATP content was on the downside: it dropped from 10.6 (pmol/ml) to 5.2 in 5min, and to 1.1 at 30min time. 2. TLP dropped from 147.679 (u/ml) to 83.818 and 38.756 under the condition of LP-I-H2O2 system for 15min and 25min respectively. The ratio of TLP to trace protein dropped from 15.379(u/mg) to 7.129 at 25min. 3.This very system made great morphological changes on Pg and Fn with the growing of the time. In general, the bacterial became bigger and longer, the edge became inconsistent and even broken to die with exudation of material inside.Conclusion: The LP-I-H2O2 system with physiological concentration of SCN" on Pg and Fn in buffer solution can effectively inhibit the growth, metabolism, pathogenesis of both Pg and Fn and can change the size and shape of both Pg and Fn. These results will provide with substantial evidence for further developing oral healthproducts with I".