Analytical Investigations of Bacterial Cellulose

The cultivation of the bacterium Acetobacter xylinus AX 5 was carried out in the common Hestrin‐Schramm medium containing D ‐glucose as C‐source and citric acid as buffer component. HPLC studies proved to be convenient methods to investigate the stability and interactions of these constituents in the starting culture liquid. Within the initial sterilization step and limited by the citric acid, up to 6% of the D ‐glucose was partially isomerized to D‐fructose and degraded to dark‐yellow products. In static culture, A. xylinus AX 5 produces cellulose extracellularly on the surface of this medium. Solid‐state NMR spectroscopy represents a suitable analytical method to characterize the supramolecular structure of the bacterial cellulose in never‐dried, air‐dried, and freeze‐dried states. It could be demonstrated that the drying process reduces the degree of crystallinity in the range of about 12% without changes in the Iα/β ratio of these cellulose modifications.