Regulatory mechanisms involved in cellulose biosynthesis by acetic acid bacteria

醋酸菌(AAB)对于许多生物技术应用是重要的，包括合成纤维素，一种未支化的1，4-吡喃葡萄糖残基的聚合物。由AAB合成的纤维素具有独特的纳米形态，由纳米纤维组成的超细网络有助于其抗张强度和高度结晶的结构。由于细菌纤维素的独特性质，它在食品、造纸、医药以及作为生物燃料生产的原料等方面有着广泛的工业应用。AAB可以从水果和花卉中分离出来；然而，纤维素在植物-微生物相互作用中所起的作用尚不清楚。胞外纤维素是许多病原体生物膜结构的重要组成部分，促进附着并提供保护。尽管纤维素作为一种微生物生存策略具有明显的重要性，但其生物合成途径，包括输出和最终组装成结晶形式，尚未被阐明。这项研究计划的长期目标是阐明细菌纤维素的完整生物合成途径，并了解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。由于细菌纤维素有许多实际的工业应用，从这项研究计划中获得的知识将是设计具有独特性能的不同应用的纤维素材料的基础。这一授权期的具体目标将是：1)鉴定在纤维素合成抑制剂存在的情况下能够合成纤维素的突变株；2)鉴定吲哚-3-乙酸和脱落酸在调节纤维素合成中的功能作用；3)阐明醋酸菌响应影响纤维素生产的环境信号所使用的调节电路。该研究项目将为微生物学、分子生物学、遗传学、蛋白质组学、生物化学和材料科学领域的高素质人才提供跨学科培训。

Acetic acid bacteria (AAB) are important for many biotechnological applications including synthesis of cellulose, an unbranched polymer of ß-1,4-linked glucopyranose residues. Cellulose synthesized by AAB has a unique nanomorphology consisting of an ultrafine network of nanofibres that contribute to its tensile strength and highly crystalline structure. Due to the unique properties of bacterial cellulose, it has many industrial applications such as food, paper, pharmaceuticals, and as a feedstock for biofuel production. AAB can be isolated from fruits and flowers; however, the role cellulose plays in this plant-microbe interaction is not known. Extracellular cellulose is a crucial component of the biofilm structure of many pathogens facilitating attachment and providing protection. Despite the obvious importance of cellulose as a microbial survival strategy, the biosynthetic pathway including export and final assembly into the crystallized form are yet to be elucidated. The long-range goal of this research program is to elucidate the complete biosynthetic pathway of bacterial cellulose and to understand 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. Since bacterial cellulose has many practical industrial applications, the knowledge gained from this research program will be fundamental in engineering cellulosic materials with unique properties for diverse applications. The specific objectives for this granting period will be to 1) characterize mutants able to synthesize cellulose in the presence of cellulose synthesis inhibitors; 2) characterize the functional role of indole-3-acetic acid and abscisic acid in regulating cellulose synthesis; 3) elucidate regulatory circuits used by acetic acid bacteria in response to environmental signals that affect cellulose production. This research program will provide interdisciplinary training to highly qualified personnel in the areas of microbiology, molecular biology, genetics, proteomics, biochemistry and material science.