Thanyasrisung P, Komatsuzawa H, Yoshimura G, Fujiwara T, Yamada S, Kozai K, Eto K, Izumi Y, Sugai M
Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
Oral Microbiol Immunol. 2009 Dec;24(6):451-5. doi: 10.1111/j.1399-302X.2009.00536.x.
Dental caries remains one of the most common chronic infectious diseases throughout the world. The formation of dental plaque is one of the caries risk factors. As a consequence, the removal of plaque may reduce the incidence of caries development. We identified an autolysin produced by Streptococcus mutans named auto-mutanolysin (Aml). Aml selectively lyses S. mutans and Streptococcus sobrinus. The specificity towards these cariogenic bacteria suggests that Aml may be used to prevent dental caries. Here, with the aim towards therapeutic application, we investigated the lytic activity of Aml against clinical isolates of S. mutans and S. sobrinus using planktonic cells and biofilms.
Planktonic cell suspensions and biofilms of clinically isolated streptococci were treated with Aml in the absence or the presence of Triton X-100. The lytic activity of Aml was monitored as the change in turbidity. The disruption of biofilms was evaluated by detecting the released DNA by polymerase chain reaction and observing the alteration of optical density of treated biofilms.
Triton X-100 enhances the lytic ability of Aml. Using planktonic cells, Aml had various lysis levels against clinical strains. Repeated Aml treatment showed disruption of the biofilm using the representative clinical strains.
Our study demonstrates that Aml has an ability to lyse planktonic and biofilm cells of clinically isolated mutans streptococci in the presence of Triton X-100. These results suggest the possibility of using Aml as an alternative or additional approach for caries prevention.
龋齿仍然是全球最常见的慢性传染病之一。牙菌斑的形成是龋齿的风险因素之一。因此，去除牙菌斑可能会降低龋齿的发病率。我们鉴定出一种由变形链球菌产生的自溶素，名为自溶变形链球菌素（Aml）。Aml可选择性地裂解变形链球菌和远缘链球菌。对这些致龋菌的特异性表明，Aml可用于预防龋齿。在此，为了实现治疗应用的目标，我们使用浮游细胞和生物膜研究了Aml对临床分离的变形链球菌和远缘链球菌的裂解活性。
在不存在或存在 Triton X-100 的情况下，用 Aml 处理临床分离的链球菌的浮游细胞悬液和生物膜。通过监测浊度变化来监测 Aml 的裂解活性。通过聚合酶链反应检测释放的 DNA 并观察处理后生物膜的光密度变化来评估生物膜的破坏情况。
Triton X-100 增强了 Aml 的裂解能力。使用浮游细胞时，Aml 对临床菌株具有不同程度的裂解作用。重复使用 Aml 处理显示，使用代表性临床菌株时生物膜被破坏。
我们的研究表明，在存在 Triton X-100 的情况下，Aml 具有裂解临床分离的变形链球菌浮游细胞和生物膜细胞的能力。这些结果表明，有可能将 Aml 用作预防龋齿的替代方法或辅助方法。
