Biofilm growth and detachment of an oral pathogen

描述：生物膜是附着在表面的细菌群落。人类80%以上的细菌感染是由生物膜造成的。由生物膜引起的疾病包括龋齿、牙周炎、囊性纤维性肺炎和感染性心内膜炎，以及各种医疗设备的感染，如静脉导管、人工关节和隐形眼镜。人们对细菌从生物膜中分离的过程知之甚少，这是感染传播到新部位所必需的过程。生物膜脱离是未来研究的一个重要领域，有望带来治疗生物膜感染的新策略。 革兰氏阴性口腔放线杆菌伴生放线杆菌被认为是局限性青少年牙周炎的病原体，这是一种严重而迅速的牙周病，每年在美国有7万人受到影响，主要是非裔美国人。伴生放线菌还会引起几种非口腔感染，包括菌血症、脑脓肿和感染性心内膜炎。新鲜临床分离的放线菌的一个显著特征是，它们能够在玻璃、塑料和唾液包裹的羟基磷灰石等表面形成极其坚韧的生物膜，这一特性已被证明对大鼠模型的毒力至关重要。对表面的紧密附着也使伴生放线菌成为体外研究生物膜生长和脱落的极佳模型。 本实验室的遗传学和显微研究表明，附着在发酵液表面的放线菌伴生菌细胞形成高度分化的生物膜菌落，能够将细胞释放到培养基中。生化和遗传学研究表明，伴生放线菌生物膜菌落由一种粘性的胞外多糖结合在一起。拟议的实验是我们初步研究的继续，该研究发现了伴生放线菌产生的一种酶，该酶会导致伴生放线菌粘性多糖膜的降解和伴生放线菌细胞从生物膜聚集体中脱落。我们计划使用基因技术来了解这种酶的产生是如何在细菌细胞中调节的，并使用生化技术来确定细胞表面的多糖物质的结构。初步数据表明，该酶能够降解其他革兰氏阴性和革兰氏阳性细菌产生的生物膜，表明它可能是一种具有广谱潜力的新型抗生物膜疗法。

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.