以Gluconacetobacter xylinus饋料批次靜置生產細菌纖維素之研究

Abstract

Bacterial cellulose (BC) is a kind of polysaccharide produced by particular strains, and it can be applied to many fields such as paper industry, food industry and biomedical materials. In contrast to plant cellulose, it has unique nano-network structure and physicochemical properties. The fed-batch process of static culture to produce BC pellicles showed that the thickness of BC pellicles was well-controlled almost infinitely with higher productivity. The production rate was maintained only under sufficient nutrients and oxygen. A fed-batch operation was to supply fresh medium on the top of BC pellicles already formed to permit the continuation of bacterial growths. In the same period of 30 days, by the fed-batch process, BC pellicles reached to a thickness of 20~40 mm, that was at least ten times of the traditional conventional static culture. In addition, by controlling the liquid height of medium added to the top of BC pellicles, the continuity between new BC pellicle and the old one was controlled. If the height was less than 1mm, the added medium the previously formed pellicle would become ‘one’ thick BC pellicle. Otherwise, it became a layer-by-layer pellicles formation process. With glucose diffusion experiments to measure the permeability of BC pellicles, similar permeability coefficient (7.735×10-6 cm2/s) for either fed-batch or conventional static process was discovered, independent of their thickness. However, the thick BC pellicle was packed so loosely that the permeability coefficient increased to 1.233×10-5(cm2/s) because of less mechanical stability. This difference was also controlled by the liquid height of medium added.