| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
Under standard culture conditions, Acetobacter xylinum produces a ribbon-like cellulose assembly, which is extruded parallel to the long axis of the bacterial cell and contains cellulose Iα rich crystals. In contrast, 'dense' and' coarse' band-like cellulose assemblies, which are extruded perpendicularly to the long axis of the cell, are produced in HS medium at 4 ℃ or on solidified HS medium at 28℃ . Structures of 'dense' and 'coarse' band-like cellulose assemblies as well as ribbon-like cellulose assembly have been investigated by TEM, AFM, X-ray diffraction analysis, and carbon-13 solid-state NMR. 'Dense' and'coarse' band-like assemblies are different in the number of strands of cellulose molecules produced from one bacterium. The 'dense' assembly gives crystalline reflections corresponding to the cellulose II type crystal in the electron and X-ray diffraction diagrams. A micrograph of the negatively stained 'dense' band-like assembly indicates that a stand is composed of the structural units, each of which is 6 - 9 nm x 10-22 nm. A separate X-ray analysis also reveals that crystallite sizes estimated from the threee quatorial reflections are 6.6, 6.7, and 8.2 nm for 'dense' band-like assembly, which are 1.4 - 2 times larger than those of cupra rayon fibers. We succeeded in obtaining AFM and TEM images of the same band-like assemblies. The height of 'dense' band-like assemblies is estimated to be 20-30 nm from their AFM height profiles. By combining AFM and TEM observations, three-dimensional information is obtained to elucidate the formation process of band-like assemblies
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