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目的:了解变异链球菌临床株体外生物膜形成规律以及不同pH对生物膜形成的影响。方法:采用微孔板培养,染色、分光光度测定法(A630)绘制体外不同pH条件下(pH=7.0～5.0)593号、18号菌株以及变异链球菌标准株(ATCC25175)的生物膜生长曲线。结果:体外变异链球菌各株在pH=5.0时均不能形成生物膜;pH=7.0时细菌生物膜形成表现为缓慢的非线性生长,12～24h生物膜开始成熟,24～36h出现一相对的生长停滞期;pH=5.0时对已形成12h的变链菌生物膜生长有明显的抑制作用,但经历12h的酸休克后各菌株的生物膜均能恢复生长。结论:变异链球菌在体外pH=7.0时于12～24h形成稳定的生物膜,该生物膜能抵抗一定程度的酸(pH=5.0)攻击,而浮游状态的细菌则不能。
Objective: To understand the biofilm formation of Streptococcus mutans in vitro and the effect of different pH on biofilm formation. Methods: The biofilm growth curves of 593, 18 strains and the standard strain of Streptococcus mutans (ATCC25175) in vitro under different pH conditions (pH = 7.0-5.0) were drawn by microplate culture, staining and spectrophotometry (A630) . Results: The biofilms could not form in vitro of Streptococcus mutans at pH = 5.0. The biofilm formation showed slow non-linear growth at pH = 7.0. The biofilm started to mature at 12 ~ 24h and a relative Growth and stagnation period. When pH = 5.0, the growth of Streptococcus mutans biofilm that had been formed for 12h was obviously inhibited, but the biofilm of each strain recovered after 12h acid shock. CONCLUSIONS: Streptococcus mutans form stable biofilms from 12 to 24 hours in vitro at pH 7.0, which is resistant to some acid (pH = 5.0) challenge, whereas bacteria in the zooplankton state do not.