Biofilm growth and detachment of an oral pathogen

描述：生物膜是附着在表面上生长的细菌群落。生物膜是造成人类80%以上细菌感染的原因。由生物膜引起的疾病的实例包括龋齿、牙周炎、囊性纤维化肺炎和感染性心内膜炎，以及各种医疗装置如静脉内导管、人工关节和隐形眼镜的感染。人们对细菌从生物膜上脱落的过程知之甚少，这是感染传播到新部位所必需的过程。生物膜分离代表了未来研究的一个重要领域，有望导致治疗生物膜感染的新策略 革兰氏阴性口腔细菌伴放线放线杆菌（Actinobacillus actinomycetemcomitans）被认为是局部青少年牙周炎的病原体，这是一种严重且快速的牙周病，每年影响美国70，000名主要是非洲裔美国人。A.伴放线菌还可引起多种非口腔感染，包括菌血症、脑脓肿和感染性心内膜炎。新鲜临床分离的A.伴随放线菌的一个重要特征是它们能够在诸如玻璃、塑料和唾液涂覆的羟基磷灰石的表面上形成极其坚韧的生物膜，该特性已被证明对于大鼠模型中的毒力是必需的。对表面的紧密粘附也使A.放线菌共生菌是研究生物膜生长和分离的良好模型。 该实验室的遗传学和显微镜研究表明，A。在肉汤中附着于表面生长的伴放线菌细胞形成高度分化的生物膜菌落，其能够将细胞释放到培养基中。生物化学和遗传学研究表明，A.伴放线菌生物膜菌落通过粘性的胞外多糖保持在一起。本实验是我们初步研究的继续，初步研究鉴定了A.放线菌共生菌引起粘性多糖涂层的降解和A.伴随放线菌的细胞从生物膜聚集。我们计划使用遗传技术来了解这种酶的产生是如何在细菌细胞中调节的，并使用生物化学技术来确定细胞表面多糖物质的结构。初步数据表明，这种酶能够降解由革兰氏阴性和革兰氏阳性细菌的其他物种产生的生物膜，这表明它可能代表具有广谱潜力的新型抗生物膜治疗剂。

DESCRIPTION: Biofilms are communities of bacteria growing attached to a surface. Biofilms are responsible for more than 80% of bacterial infections in humans. Examples of diseases caused by biofilms include Dental caries, periodontitis, cystic fibrosis pneumonia, and infective endocarditis, and infections of various medical devices such as intravenous catheters, artificial joints and contact lenses. Little is known about the detachment of bacteria from biofilms, a process necessary for the spread of infections to new sites. Biofilm detachment represents an important area of future research that is expected to lead to novel strategies for treating biofilm infections The Gram-negative oral bacterium Actinobacillus actinomycetemcomitans has been implicated as the causative agent of localized juvenile periodontitis, a severe and rapid form of periodontal disease that affects 70,000 primarily African-Americans in the U.S. annually. A. actinomycetemcomitans also causes several non-oral infections including bacteremias, brain abscesses and infective endocarditis. A striking feature of fresh clinical isolates of A. actinomycetemcomitans is their ability form extremely tenacious biofilms on surfaces such as glass, plastic and saliva-coated hydroxyapatite, a property that has been shown to be essential for virulence in a rat model. Tight adherence to surfaces also makes A. actinomycetemcomitans an excellent model for studying biofilm growth and detachment in vitro. Genetic and microscopic studies in this laboratory have shown that A. actinomycetemcomitans cells grown attached to surfaces in broth form highly-differentiated biofilm colonies that are capable of releasing cells into the medium. Biochemical and genetic studies indicate that A. actinomycetemcomitans biofilm colonies are held together by a sticky, extracellular polysaccharide. The proposed experiments are a continuation of our preliminary studies which have identified an enzyme produced by A. actinomycetemcomitans which causes the degradation of the sticky polysaccharide coating and detachment of A. actinomycetemcomitans cells from the biofilm aggregate. We plan to use genetic techniques to understand how production of this enzyme is regulated in the bacterial cell, and biochemical techniques to determine the structure of the polysaccharide substance on the surface of the cell. Preliminary data indicate that this enzyme is capable of degrading biofilms produced by other species of Gram-negative and Gram-positive bacteria, indicating that it may represent a novel anti-biofilm therapeutic with broad spectrum potential.