Control of the crystal structure of microbial cellulose during nascent stage

The structure of the product, from an Acetobacter culture in the presence o f Fluorescent Brightener, Direct Red 28, and Direct Blue 1, 14, 15 and 53, characterized by an X-ray diffractometer is a crystalline complex. On the o ther hand, solid-state C-13-NMR spectroscopy reveals that the product is no ncrystalline. However, the X-ray result of the product sample suggests that the dye molecule is included in the form of a monolayer between the cellul ose sheets in the complex corresponding to the (1(1) over bar 0) plane of m icrobial cellulose. But the celluloses regenerated from the Fluorescent Bri ghtener product, the Direct Red 28 product, and the rest of the dye product s are celluloses I IV, and II, respectively. More specifically, the C-13-NM R spectra revealed that the crystal types of cellulose from the Fluorescent Brightener and Direct Red 28 products are I-beta and IVI, respectively. Th us, the crystal structure of the product and the regenerated cellulose depe nds mainly on the position and number of the sulfonate groups in a direct d ye and the interactions of the dye with the noncrystalline microbial cellul ose in the nascent stage. The conformation and arrangement of the nascent c ellulose chain changes when a direct dye adheres to it. (C) 2000 John Wiley & Sons, Inc.