耐酸血链球菌拮抗变异链球菌作用机制的初步研究  

Action mechanisms of acid-resistant Streptococcus sanguis against Streptococcus mutans

作　　者：姜秀[1] 孙应明[1] 陶睿 张梦洁 侯梦瑶 

机构地区：[1]安徽医科大学无锡临床学院,无锡医学硕士研究生214044 [2]解放军第一〇一医院口腔科,无锡214044

出　　处：《医学研究生学报》2017年第4期371-375,共5页Journal of Medical Postgraduates

基　　金：国家自然科学基金(81300877)

摘　　要：目的血链球菌是龋病替代疗法的可能候选菌,但其在酸性环境中生长不具优势,文中旨在构建血链球菌耐酸株,研究其拮抗变异链球菌的作用机制和耐酸机制。方法通过培养基酸化培养构建血链球菌耐酸株,观察其生长情况,以及能否抵抗致死性p H值的杀伤、存活率来测定适应性耐酸能力;通过平板实验了解血链球菌和变异链球菌的竞争关系。通过实时定量PCR检测相关耐酸基因的变化。结果血链球菌Ss及其耐酸株Ss N生长受到p H值的限制,无论在酸性还是在正常环境中耐酸株的生长情况总是优于原血链菌株。血链球菌的致死性p H值为3.6,其耐酸株的致死性p H值为2.3,且其耐酸株在p H3.6的环境中存活率为66.59%;变异链球菌的致死性p H值为2.5,其耐酸株的致死性p H值为2.1,且其耐酸株在p H 2.5的环境中存活率为2.55%。当有氯霉素存在时,耐酸株不能在致死p H值环境存在。无论正常或酸性环境中,血链球菌耐酸株对变异链球菌的竞争排斥作用均强于血链球菌。与原菌相比,耐酸株长期在亚致死性p H环境中生长,其耐酸相关基因Groel、Dnak上调明显,分别为原菌的(24.29±10.37)、(30.86±8.82)倍(P<0.05)。结论血链球菌具有适应性耐酸能力,在亚致死性p H值中生长能诱导耐酸性提高。构建耐酸血链球菌运用替代疗法可能为治疗龋病提供新思路。Objective Streptococcus sanguis is a possible candidate bacterium for the caries replacement therapy, which has no advantages in the acidic environment. The aim of the study was to construct acid-resistant strains of Streptococcus sanguis, determine its acid tolerance, and explore the mechanism of its antagonism against Sterptococcus mutans. Methods By gradually reducing the pH value of the medium, we constructed acid-resistant strains of Streptococcus sanguis, observed their growth and measured their acid tolerance according to their survival rate against lethal pH. We evaluated the competitive relationship between Streptococcus sanguis and Streptococcus mutans by plate experiment and detected the changes of related acid resistance genes by real-time quantitative PCR. Results The growth of Streptococcus sanguis and its acid-resistant strains were limited by the pH value, and that of Streptococcus san- guis was better in either acidic or normal environment. The lethal pH value of Streptococcus sanguis was 3.6, that of its acid-resistant strains was 2.3, and the survival rate of the acid-resistant strains was 66.59% in the pH 3.6 environment. In comparison, the lethal pH value of Streptococcus mutans was 2.5, that of its acid-resistant strains was 2.1, and the survival rate of the acid-resistant strains was2.55% in the pH 2.5 environment. In the presence of chloramphenicol, the acid-resistant strains could not survive in the original lethal pH. In the sub-lethal pH environment, the expressions of the acid resistance- related genes Groel and Dnak in the acid-resistant strains were signifi- cantly up-regulated as compared with those in the original Streptococ- cus sanguis （P〈0.05）. Conclusion Streptococcus sanguis has an acid adaptability and can enhance acid resistance in the sub-lethal pH environment. Acid-resistant Streptococcus sanguis in the replace- ment therapy may provide some new ideas for the treatment of dental caries.

关 键 词：耐酸 血链球菌 龋病 拮抗 

分 类 号：R781.1[医药卫生—口腔医学]