GENETIC ANALYSIS OF ORAL STREPTOCOCCAL BIOFILM FORMATION

口腔草绿色链球菌（包括戈登链球菌）最初在牙齿表面定植，导致最终形成称为牙菌斑的生物膜。人类最常见的疾病，龋齿和牙周病，是由于口腔微生物菌群的不平衡而导致的，这使得致病物种占主导地位。最初的牙菌斑形成的特征是细菌（如链球菌）的粘附细胞通过获得性表膜的特定唾液蛋白粘附到牙齿表面。这些最初的定居者和其他细菌在非生物表面上的随后生长导致牙菌斑的形成。研究已经广泛地表征了嗜酸性细菌与唾液涂层/羟基磷灰石表面的初始结合，但是触发从嗜酸性到固着生活模式的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。据推测，新的基因是需要初始的牙齿生物膜的形成，和这些基因的鉴定和表征其表达将是至关重要的发展的新方法的牙菌斑控制。本研究将使用一种简单但有效的聚苯乙烯表面微生物积累方法来表征S. gordonii使用Tn 916转座诱变，（2）生物膜缺陷突变体的表征，和（3）生物膜基因的克隆和遗传分析。这些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将是至关重要的新的治疗策略的发展，以修改牙齿生物膜植物群的组成，在健康中发现。

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.