GENETIC ANALYSIS OF ORAL STREPTOCOCCAL BIOFILM FORMATION

包括戈登链球菌在内的口腔绿链球菌最初在牙齿表面定植，导致最终形成称为牙菌斑的生物膜。龋齿和牙周病是人类最常见的疾病，是由于口腔微生物群失衡造成的，这使得致病物种占主导地位。牙菌斑最初形成的特点是细菌的浮游细胞，如链球菌，通过获得性牙膜的特定唾液蛋白粘附到牙齿表面。这些最初的定植菌和其他细菌随后在非生物表面生长，导致牙菌斑的形成。研究已经广泛地描述了浮游细菌与唾液涂层/羟基磷灰石表面的初始结合，但是触发从浮游生物到无根生命模式的转变以及随后的牙齿生物膜积累的先决条件信号却知之甚少。据推测，新的基因是初始牙菌斑生物膜形成所必需的，而这些基因的鉴定和表达特征的表征将对牙菌斑控制新方法的发展至关重要。本研究将采用一种简单而有效的微生物在聚苯乙烯表面积累的方法来鉴定利用Tn916转糖诱变分离的哥氏链球菌生物膜缺陷突变体，(2)生物膜缺陷突变体的鉴定，(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来改变牙齿生物膜菌群的组成，使其朝着健康的方向发展至关重要。

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.