数学模型法研究L．casei LC2W对H.pylori SS1黏附MKN-45细胞的抑制作用

目的研究干酪乳杆菌LC2W对幽门螺杆菌（H.pylori）SS1黏附MKN-45的抑制作用，探讨益生菌对致病菌拈抗的机制。方法体外培养人胃癌细胞MKN-45，采用平板计数的方法研究2株细菌的黏附性质；引入数学模型，比较LC2W与H.pylori SS1的竞争、排除和替代作用。结果运用模型可以估算出LC2W和H.pylori SS1对MKN-45最大黏附数和亲和力的大小，并可以预测在混合体系中2种菌黏附的比例；实验发现LC2W对H.pylori SS1的黏附具有很强的竞争作用和排除作用，且这2种作用存在明显的量效关系。LC2W对H.pylori SS1的黏附的替代作用不明显或过程非常缓慢。结论所采用的数学模型能较好的模拟LC2W和H.pylori SS1黏附及LC2W对H.pylori SS1黏附抑制作用，这种抑制作用主要是通过竞争性占位形成的。

The study of antagonistic activity of Lactobacillus casei LC2W against Helicobacter pylori SS1 for adhesion to MKN-45 cells by mathematical models

Objective To study the antagonistic activity of Lactobacillus casei LC2W against Helicobacter pylori SS1 for adhesion to MKN-45 cells and explicate the phenomena of bacterial adhesion and inhibition.Methods Gastric-cell line MKN-45 was cultured in vitro,plate counting was used to study the adhesive ability of the two strains;mathematical models based on a simple dissociation process were developed and the competition,exclusion and displacement between the two strains were compared according to the models.Results The equations obtained from the models allow the estimation of the maximal number of LC2W and Helicobacter pylori SS1 cells that could adhere to MKN-45 cells respectively;they also characterized the affinity of the bacteria to MKN-45 cells and the theoretical adhesion ratio of two bacteria present in a mixed suspension.The results showed that there were significant competition and elimination of Helicobacter pylori SS1 by LC2W,both of which were dependent on concentration of LC2W;the displacement of Helicobacter pylori SS1 by LC2W was insignificant or slow.Conclusions The mathematical models were suitable for simulating the adhesion and the antagonistic activity of LC2W against Helicobacter pylori SS1 for adhesion to MKN-45 cells,which meant the antagonistic activity was mainly attributed to the competitive space occupying between the two strains.