Completely amorphous cellulose biosynthesized in agitated culture at low temperature.

The morphology and structure of the biosynthesized cellulose are related to the culture methods and conditions. In order to investigate the detail culture conditions, the Gluconacetbacter xylinum 1.1812 (ATCC 23767) strains were cultivated in static culture at 12 and 30 °C, and agitated culture at 12 °C. The cellulose samples were analyzed by FESEM, FTIR, CP/MAS 13C NMR, WAXRD and TGA. The cellulose membrane produced in static medium at 30 °C is made up of the microfibrils with a width of 60-90 nm, which has highest crystallinity index and the most content of cellulose Iα. The cellulose membrane produced in static medium at 12 °C is accumulated by the pellicles with a thickness of ~10 nm and a width of 700-3000 nm, which is cellulose I crystalline structure. The macroscopic sphere-like cellulose produced in agitated culture at 12 °C is composed of flat, strongly twisted cellulose bands with a width of 700-1200 nm, and reveals completely amorphous structure which exhibits only the diffuse X-ray diffraction pattern, lack of characteristic crystalline peaks. This work provides a new method to prepare amorphous cellulose.