GENETIC ANALYSIS OF ORAL STREPTOCOCCAL BIOFILM FORMATION

口腔绿色链球菌，包括戈登链球菌，最初在牙齿表面定植，最终导致称为牙菌斑的生物膜的形成。人类最常见的疾病，龋齿和牙周病，是由于口腔微生物区系失衡造成的，这使得致病物种占据主导地位。初始菌斑形成的特征是通过获得性牙膜的特定唾液蛋白将链球菌等细菌的浮游细胞附着到牙齿表面。这些最初的定殖者和其他细菌随后在非生物表面生长，导致牙菌斑的形成。研究已经广泛地表征了浮游细菌最初与唾液涂层/羟基磷灰石表面的结合，但触发从浮游到固着的生活模式转变以及随后的牙齿生物膜积累的先决条件信号知之甚少。新的基因被认为是牙科生物膜形成所必需的，鉴定这些基因并表征它们的表达将是开发新的牙菌斑控制方法的关键。本研究将使用一种简单而有效的聚苯乙烯表面微生物聚集方法，通过Tn916转座糖诱变分离戈登葡萄球菌生物膜缺陷突变株，(2)生物膜缺陷突变株的特征，以及(3)生物膜基因的克隆和遗传分析。这些关于链球菌生物膜形成的研究将为牙菌斑形成的初始阶段提供有价值的信息。了解生物膜形成的机制对于开发新的治疗策略以改变牙齿生物膜菌群的组成以适应健康是至关重要的。

Initial colonization of tooth surfaces by oral viridans streptococci, including Streptococcus gordonii, leads to the eventual formation of biofilms called dental plaque. The most common disease of man, caries and periodontal disease, result from imbalances in the oral microflora, which allow pathogenic species to dominate. Initial plaque formation is characterized by the adhesion of planktonic cells of bacteria such as streptococci to tooth surfaces via specific salivary proteins of the acquired pellicle. Subsequent growth of these initial colonizers and other bacteria on the abiotic surface leads to the formation of dental plaque. Studies have extensively characterized of the initial binding of the planktonic bacteria to saliva-coated/hydroxyapatite surfaces, but the prerequisite signals that trigger the transition from a planktonic to a sessile mode of life and the subsequent accumulation of dental biofilms are poorly understood. It is hypothesized that novel genes are required for initial dental biofilm formation, and identification of such genes and characterization of their expression will be crucial for the development of novel methods of dental plaque control. A simple, but effective method of microbial accumulation on polystyrene surfaces will be used in this study to characterize isolation of biofilm-defective mutants of S. gordonii using Tn916 transposan mutagenesis, (2) characterization of biofilm-defective mutants, and (3) cloning and genetic analyses of biofilm genes. These studies of biofilm formation in streptococci will provide valuable information on the initial stages of dental plaque formation. Understanding the mechanisms involved in biofilm formation will be crucial for the development of novel therapeutic strategies to modify the composition of dental biofilm flora towards that found in health.