中文摘要：

链球菌 mutans，一个克积极的容许的厌氧的细菌，被认为是为牙齿的龋的一个主要 etiological 因素。在 thisstudy，从龋活跃、没有龋的个人的牙齿的瓷釉表面的匾为 S 被获得并且栽培。mutans 隔离。形态学检查，生物化学的描述，和聚合酶链反应被执行到识别。mutans。S 的 cariogenicity。从临床的标本孤立的 mutans 种类被测试细菌的 acidogenicity， aciduricity，细胞外的 polysaccharideproduction，和粘附能力评估。最后，减少性的 SELEX (由 exponentialenrichment 的 ligands 的系统的进化) 指向整个未经触动的房间的技术与 highcariogenicity 为对种类特定的 ssDNA aptamers 习惯于屏幕。在九轮减少性的 SELEX 以后，足够的水池丰富是由放射性的 isotopeanalysis 出现被完成。充实的水池随机被克隆并且定序，由联机的 MEME 和 RNA 结构软件 analysisof 列在后面序列。从流动 cytometry 的结果显示了那 aptamers H1， H16， H4， L1， L10，和 H19 能 discriminatehighly cariogenic S。mutans 紧张从糟糕， cariogenic 拉紧。在这些之中， Aptamer H19 与 cariogenic S 有最强壮的有约束力的能力。有 69.45 的一个分离常数的 mutans 紧张 ? 畣慬? 敭档湡獩獭漠 ??? 湡 ? 桴 ? 潰整瑮慩? 敮 ? 桴牥灡略楴? 瑳慲整楧獥潦 ? 桴 ? 牴慥浴湥 ? 景琠楨?湩敦瑣潩 n

英文摘要：

Streptococcus mutans, a Gram-positive facultative anaerobic bacterium, is considered to be a major etiological factor for dental caries. In this study, plaques from dental enamel surfaces of caries-active and caries-free individuals were obtained and cultivated for S. mutans isolation. Morphology examination, biochemical characterization, and polymerase chain reaction were performed to identify S. mutans. The cariogenicity of S. mutans strains isolated from clinical specimens was evaluated by testing the acidogenicity, aciduricity, extracellular polysaccharide production, and adhesion ability of the bacteria. Finally, subtractive SELEX （systematic evolution of ligands by exponential enrichment） technology targeting whole intact cells was used to screen for ssDNA aptamers specific to the strains with high cariogenicity. After nine rounds of subtractive SELEX, sufficient pool enrichment was achieved as shown by radioactive isotope analysis. The enriched pool was cloned and sequenced randomly, followed by MEME online and RNA structure software analysis of the sequences. Results from the flow cytometry indicated that aptamers H1, H16, H4, L1, L10, and H19 could discriminate highly cariogenic S. mutans strains from poorly cariogenic strains. Among these, Aptamer H19 had the strongest binding capacity with cariogenic S. rnutans strains with a dissociation constant of 69.45 ±38.53 nM. In conclusion, ssDNA aptamers specific to highly cariogenic clinical S. mutans strains were successfully obtained. These ssDNA aptamers might be used for the early diagnosis and treatment of dental caries.