Host-associated biofilm formation and dispersal mechanisms

摘要 细菌可以形成多细胞群落，其中单个细胞受到保护，不受环境影响。 由于被包裹在由多糖组成的保护性基质中而造成的侮辱，如抗生素 和其他大分子，[2]与自由生活的浮游细胞在生理上不同。生物膜形成 增强细菌在表面定居的能力，包括宿主组织和非生物表面，如医用 植入物，并通过传播过程在远端位置播撒后续感染。由于这些原因， 特征，生物膜中的细菌是大多数医院获得性感染的原因，因此 了解生物膜是如何形成和分散的是至关重要的。虽然数量众多的动物 已经开发了生物膜形成的模型，几乎没有允许目视检查生物膜形成的模型 和扩散事件以及对随后的殖民结果的量化分析。一个如此健壮的人 然而，这种模式可以在鱼类弧菌与鱿鱼(Euprymna Scolope)的共生中找到。殖民，V。 鱼腥藻首先在共生器官表面形成生物膜，然后分散进入共生器官并 最终定居在这个器官深处的地方。我们的工作表明，生物膜形成所需的基因 在实验室培养中，寄主相关(HA)生物膜和定植同样需要，而基因 在实验室中促进生物膜形成的变化也显著地增强了HA生物膜和定植。这 强相关性为我们提供了一个特殊的机会来开发和测试关于这些机制的假说 腐植酸生物膜、扩散和随后的定植。我们的工作揭示了HA生物膜和 定植依赖于SYP，一个参与SYP多糖生产的18个基因座，以及多个 控制SYP转录和转录后事件的传感器激酶和反应调节器。我们有 最近发现，钙(Ca~(2+))和一氧化氮(NO)分别是血管紧张素转换酶的强诱导剂和抑制因子。 生物膜的形成。CA2是一种生理上相关的信号，它似乎影响许多过程，但如何 它是如何做到这一点的-目前尚不清楚。不，它是由鱿鱼产生的，已知会影响HA生物膜，可能 影响SYP转录所需的一种传感器激酶，我们建议评估潜在的 机械装置。我们还准备确定其他促进/抑制HA生物膜的生理信号。我们 最近发现了在实验室培养中可以看到扩散的条件，并已经 观察到费氏弧菌在完全生长的培养物中经历了多轮形成和扩散，结果 这表明是由转录后机制控制的。我们已经开始通过以下方式调查这一进程 确定一组与控制扩散有关的基因。我们建议发展一种机械性的理解 这些扩散基因和控制扩散事件的因素以及寻找我们 预言将会存在。我们预计，这项工作将为了解细菌 对它们的环境做出反应，并在动物宿主内进入和离开多细胞群落。

Abstract Bacteria can form multi-cellular communities in which individual cells are protected from environmental insults such as antibiotics by virtue of being [1] encased in a protective matrix comprised of polysaccharides and other macromolecules and [2] physiologically distinct from free-living, planktonic cells. Biofilm formation enhances the ability of bacteria to colonize surfaces, including host tissues and abiotic surfaces such as medical implants, and seeds subsequent infections at distal locations through dispersal processes. As a result of these characteristics, bacteria in biofilms are responsible for the majority of hospital-acquired infections and thus understanding how biofilms form and disperse from such biofilms is critical. Although numerous animal models of biofilm formation have been developed, few, if any, permit visual examination of biofilm formation and dispersal events as well as a quantitative analysis of subsequent colonization outcomes. One such robust model, however, can be found in the Vibrio fischeri-squid (Euprymna scolopes) symbiosis. To colonize, V. fischeri first forms a biofilm on the surface of the symbiotic organ, then disperses from it to enter and ultimately colonize sites deep within this organ. Our work has shown that genes required for biofilm formation in laboratory culture are similarly required for host-associated (HA) biofilms and colonization, while genetic changes that enhance biofilm formation in the lab also strikingly enhance HA biofilms and colonization. This strong correlation affords us an exceptional opportunity to develop and test hypotheses about the mechanisms of HA-biofilms, dispersal and subsequent colonization. Our work has revealed that HA biofilms and colonization depend on syp, an 18-gene locus involved in production of SYP polysaccharide, and on multiple sensor kinases and response regulators that control syp transcription and post-transcriptional events. We have recently identified calcium (Ca2+) and nitric oxide (NO) as a strong inducer and inhibitor, respectively, of biofilm formation. Ca2+ is a physiologically relevant signal that appears to affect numerous processes, but how it does so is as-yet unknown. NO, which is produced by the squid and known to influence HA-biofilms, likely impacts one of the sensor kinases required for syp transcription, and we propose to evaluate the underlying mechanisms. We are also poised to identify other physiological signals that promote/inhibit HA biofilms. We have recently uncovered conditions in which dispersal can be visualized in laboratory culture, and have observed that V. fischeri undergoes multiple rounds of formation and dispersal in fully-grown cultures, a result that suggests control by post-transcriptional mechanisms. We have begun to investigate that process by identifying a set of genes involved in controlling dispersal. We propose to develop a mechanistic understanding of these dispersal genes and the factors that control dispersal events as well as to search for others that we predict to exist. We anticipate that this work will provide insights into the mechanisms by which bacteria respond to their environment and transition in and out of multi-cellular communities within an animal host.