Regulatory mechanisms involved in cellulose biosynthesis by acetic acid bacteria

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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.