Direct dyes and fluorescent brightening agents (which hydrogen bond with cellulose) and carboxymethylcellulose (which closely associates with native cellulose) have been used in vivo to alter cellulose assembly by the gram-negative bacterium Acetobacter xylinum. The dyes and brighteners alter cellulose biogenesis at a different level of fibril organization than carboxymethylcellulose. Light and electron microscopy, X-ray diffraction, and biochemical kinetics have been used to examine the nature of these alterations. From these data, we have proposed (1,2,3) that polymerization and crystallization are coupled processes which can be experimentally separated in vivo, and that biogenesis of cellulose I fibrils occurs by a cell-directed, self-assembly process in A. xylinum. The relationship of such a mechanism to control of fibril substructure and width, and to control of crystallite size in A. xylinum, algae, and higher plants is discussed.

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Last modified 27 October 2005.
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