Mechanisms Involved in Bacterial Cellulose Biosynthesis

大肠杆菌和沙门氏菌形成高度耐药的生物膜，由纤维素和卷曲菌组成，这有助于这些细菌逃避免疫系统的检测，并增加它们对抗菌剂和恶劣环境因素的耐受性。纤维素成分特别赋予保护免受机械、化学和生物压力，并促进粘附在许多表面，如上皮细胞、各种食物、水分配系统等。因此，了解生物膜的形成和组成对于理解这些细菌如何在环境水库中建立自己至关重要，从而使它们继续威胁我们的食物/水安全、工业过程和一般健康。细菌纤维素也获得了生物工程意义，因为它具有独特的物理/化学性质，与藻类或植物来源的纤维素相比，提供了显着的优势。这些特性已被成功地用于生产新型伤口敷料、生物塑料、生物燃料和组织再生的生物惰性支撑。尽管细菌纤维素的生物和工业意义正在扩大，但人们对细菌合成和出口这种聚合物知之甚少。遗传学研究表明，bcsABZCEFG等7个基因对肠道细菌的纤维素生物合成至关重要。我们假设Bcs蛋白聚集在一起形成细菌细胞壁跨越复合体，促进纤维素从细胞中协调聚合、输出和释放。利用大肠杆菌作为模型系统，我们的目标是利用多学科方法来表征参与这些过程的每种蛋白质的结构和功能。这项研究的结果将是揭示绕过生物膜屏障的独特方法的关键，并将为设计具有特定性能的聚合物（或酶）奠定基础，用于医疗/工业应用。同样重要的是，对纤维素合成/输出的详细了解将导致发现与多糖合成和细菌物种间生物膜发育有关的重要原理。

Escherichia and Salmonella species form highly resistant biofilms, composed of cellulose and curli fimbriae, that helps these bacteria elude detection by the immune system and increases their tolerance to antimicrobial agents and harsh environmental factors. The cellulose component specifically confers protection from mechanical, chemical and biological stresses and promotes adherence to a number of surfaces, such as epithelial cells, a variety of foods, water distribution systems and more. Thus, knowledge of biofilm formation and composition is of critical importance to understanding how these bacteria establish themselves in environmental reservoirs, thereby enabling them to continue to threaten our food/water security, industrial processes and general health. Bacterial cellulose is also gaining bioengineering significance as it has unique physical/chemical properties that provide significant advantages when compared to algal or plant derived cellulose. These properties have been successfully exploited for the generation of novel wound dressings, bio-plastics, biofuels and bio-inert supports for tissue regeneration. Even though the biological and industrial implications of bacterial cellulose are expanding, little is known about the synthesis and export of this polymer by bacteria. Genetic studies have demonstrated that seven genes, bcsABZCEFG, are essential for the biosynthesis of cellulose in Enteric bacteria. We hypothesize that the Bcs proteins come together to form a bacterial cell wall spanning complex that facilitates the coordinated polymerization, export and release of cellulose from the cell. Using E. coli as a model system, our goals are to utilize a multidisciplinary approach to characterize the structure and function of each of the proteins involved in these processes. The results of this research will be key to revealing unique approaches to circumvent the biofilm barrier and will and lay the groundwork for designing polymers (or enzymes) with specific properties for medical/industrial applications. Equally important, a detailed understanding of the synthesis/export of cellulose will lead to the discovery of important principles relating to polysaccharide synthesis and biofilm development across bacterial species.