Acetobacter xylinum crystalline native cellulose

It has been known for some time that the more crystalline native celluloses from algae and from Acetobacter xylinum produce diffraction patterns that have many features in common with those of the crystalline celluloses from the higher plants, such as ramie, but that cannot be indexed as simply or on the basis of the same unit cell. The new information from the CP-MAS UMR spectra, together with that from the Raman spectra, suggests some bases for understanding these differences, and directions for further explora-t ions. 

The bacterial cellulose synthase from Acetobacter xylinum can be solubilized with detergents, and the resulting enzyme generates characteristic 1.7 ran cellulose fibrils (Fig. 20-4) from UDP-glucose.125/127-129 These are similar, but not identical, to the fibrils of cellulose I produced by intact bacteria.125 130 Each native fibril appears as a left-handed helix which may contain about nine parallel chains in a crystalline array. Three of these helices appear to coil together (Fig. 20-4) to form a larger 3.7-nm left-handed helical fibril. Similar fibrils are formed by plants. In both... 

A survey of several native celluloses reinforced the similarity of the higher plant celluloses to one another, although limits of resolution and questions of chemical purity in the cellulose chains make comparison difficult and less meaningful. A parallel survey of NMR spectra from the more chemically pure algal celluloses and the bacterial cellulose, Acetobacter xylinum, indicated a general uniformity, albeit these spectra were distinct from the spectra of the higher plant celluloses. These algal cellulose spectra, however, showed small variations, outside of experimental error, which were taken as evidence for crystalline polymorphy. 

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