Discovering the regulatory mechanisms involved in bacterial cellulose biosynthesis

胞外纤维素是一种未支化的1，4-吡喃葡萄糖残基的聚合物，是许多植物和人类病原体生物膜结构的重要组成部分，有助于它们附着在表面并提供对环境应激源的保护。尽管纤维素作为一种微生物生存策略具有明显的重要性，但环境信号调节这种重要生物聚合物的合成的机制尚不清楚。醋酸菌(AAB)在酸性、糖类和富酒精环境中普遍存在。这些革兰氏阴性细菌对许多生物技术应用都很重要，包括合成细菌纤维素(BC)。由AAB合成的BC由超细的纳米纤维网络组成，这有助于其高度结晶的结构和抗张强度，使其在许多工业应用中具有重要意义，如纸张、药品、伤口敷料和组织支架。AAB可以从水果和花卉中分离出来，然而，纤维素在这种植物-微生物相互作用中所起的作用尚不清楚。这项研究计划的长期目标是阐明影响纤维素合成和物理化学性质的多个水平的调控。这一知识对于了解细菌纤维素在微生物-植物相互作用中所起的作用以及纤维素的性质如何影响细菌在环境中的生存至关重要。从这项研究计划中获得的知识将是为各种工业应用设计具有独特性能的纤维材料的基础，并将是找到控制纤维生物膜的监管目标的重要一步。为了在我们最新工作的基础上，进一步阐明控制纤维素介导的植物-微生物相互作用的调控电路，本授权期的具体目标将是：1)鉴定转录调控因子FIXK在BC生物合成中的功能作用；2)鉴定植物激素在BC合成调控中的作用；3)鉴定BC生物合成的关键植物激素反应调节因子。这一研究计划将为微生物学、分子生物学、遗传学、蛋白质组学、转录组学、生物信息学、生物化学和材料科学领域的高素质人员提供跨学科培训。

Extracellular cellulose, an unbranched polymer of ß--1,4-linked glucopyranose residues, is a crucial component of the biofilm structure of many plant and human pathogens facilitating their attachment to surfaces and providing protection against environmental stressors. Despite the obvious importance of cellulose as a microbial survival strategy, the mechanisms by which environmental signals regulate the synthesis of this important biopolymer are unknown. Acetic acid bacteria (AAB) are ubiquitous in acidic, sugary and alcohol-rich environments. These gram-negative bacteria are important for many biotechnological applications including the synthesis of bacterial cellulose (BC). BC synthesized by AAB consists of an ultrafine network of nanofibres that contribute to its highly crystalline structure and tensile strength making it important for many industrial applications such as paper, pharmaceuticals, wound dressings and tissue scaffolds. AAB can be isolated from fruits and flowers, however, the role cellulose plays in this plant-microbe interaction is not known. The long-range goal of this research program is to elucidate the multiple levels of regulatory control that affect not only the synthesis but also the physicochemical properties of cellulose. This knowledge is key to understanding the role bacterial cellulose plays in microbe-plant interactions and how the cellulose properties affect bacterial survival in the environment. The knowledge gained from this research program will be fundamental in engineering cellulosic materials with unique properties for diverse industrial applications and will be an important step towards finding regulatory targets for the control of cellulosic biofilms. To build on our recent work in this area and to further elucidate the regulatory circuits that control cellulose-mediated plant-microbe interactions, the specific objectives for this granting period will be to 1) characterize the functional role of FixK, a Crp/Fnr transcriptional regulator, in BC biosynthesis; 2) characterize the role phytohomones play in BC regulation; and 3) identify key phytohormone-responsive regulators of BC biosynthesis. This research program will provide interdisciplinary training to highly qualified personnel in the areas of microbiology, molecular biology, genetics, proteomics, transcriptomics, bioinformatics, biochemistry and material science.