Discovering the regulatory mechanisms involved in bacterial cellulose biosynthesis

胞外纤维素是一种由-1,4-链葡萄糖醛酸残基组成的未支链聚合物，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，并提供对环境胁迫的保护。尽管纤维素作为微生物生存策略的重要性显而易见，但环境信号调节这种重要生物聚合物合成的机制尚不清楚。醋酸细菌（AAB）在酸性、含糖和富含酒精的环境中无处不在。这些革兰氏阴性菌对包括细菌纤维素（BC）合成在内的许多生物技术应用都很重要。由AAB合成的BC由纳米纤维的超细网络组成，这有助于其高度结晶结构和拉伸强度，使其在许多工业应用中发挥重要作用，如造纸，制药，伤口敷料和组织支架。AAB可以从水果和花朵中分离出来，然而，纤维素在这种植物-微生物相互作用中的作用尚不清楚。本研究计划的长期目标是阐明不仅影响纤维素合成而且影响纤维素理化性质的多种调控水平。这些知识是理解细菌纤维素在微生物与植物相互作用中的作用以及纤维素特性如何影响细菌在环境中的生存的关键。从该研究项目中获得的知识将是工程纤维素材料的基础，具有独特的性能，适用于各种工业应用，并将是寻找纤维素生物膜控制调控目标的重要一步。为了进一步阐明纤维素介导的植物与微生物相互作用的调控回路，本授权期的具体目标将是：1)表征Crp/Fnr转录调节剂FixK在BC生物合成中的功能作用；2)描述植物激素在BC调控中的作用；3)确定BC生物合成的关键植物激素响应调节因子。该研究项目将为微生物学、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等领域的高素质人才提供跨学科培训。

Extracellular cellulose, an unbranched polymer of --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.