TEM study of band-like cellulose assemblies produced by Acetobacter xylinum at 4 °C

Two kinds of band-like cellulose assemblies, coarse and dense structures, are produced in Hestrin-Schramm medium at 4 degreesC using smooth colonies isolated from Acetobacter xylinum ATCC23769, whereas ribbon cellulose assemblies are produced by the same colonies at 28 degreesC. The dense and the coarse band-like assemblies consist of many strand-like cellulose entities ('strands') and are extruded perpendicularly to the long axis of the bacterial cell. In an early stage of incubation at 4 degreesC, the dense band-like assembly is produced and the number of strands decreases gradually with increasing incubation time at 4 degreesC, probably because the number of active TC subunits decreases as a result of the low-temperature shock for the bacteria. In contrast, the coarse band-like assembly is clearly observed after about 1 h of incubation at 4 degreesC. The number of strands in the coarse band-like assembly is about one third of that of the dense band-like assembly and does not change during the incubation time of about 6 h. In the selected-area electron diffraction (ED) experiment, the dense band-like assembly gives crystalline reflections corresponding to the cellulose II type crystal, while the coarse band-like assembly does not give any crystalline reflections under the same ED conditions.