We have been extensively studying both top-down and bottom up processes to fabricate β-1,4 or β-1,3 glucan nano-objects using water and biological systems. Concerning the bottom up processes, the following two results can provide the alternative idea of β-1,4 or β-1,3 glucan to firstly appear. As a native nanoglucan-producing system, a fiber bundle composed of hollow nano-fibrils was found to be secreted from protoplasts of white birch (Betula platyphylla) leaves callus efficiently in an acidic medium containing high concentration of Ca2＋[1]. The stress culture condition for the fiber secretion was severe not to be found at the present environment. The 13C NMR spectra indicated that the component nanofibers are not composed of linear (1→4)-β-glucan (cellulose), but of linear (1→3)-β-glucan without branches (callose). The information so far obtained on how callose is capable to establish a nanofiber will be provided in this presentation. As a bio-architecture using Gluconacetobacter xylinus (G. xylinus), we have recently developed a novel gene-transformation route for the production of bacterial cellulose/curdlan (β-1,3-glucan) nanocomposites by separate but simultaneous in vivo synthesis of cellulose and curdlan[2]. Modification of the cellulose-nanofiber-producing system of G. xylinus enabled curdlan to be synthesized simultaneously with cellulose nanofibers in vivo, resulting in biopreparation of nanocomposites. The obtained curdlan/cellulose composites were characterized, and their properties were compared with those of normal bacterial cellulose pellicles, indicating that curdlan mixed with the cellulose nanofibers at the nanoscale without disruption of the nanofiber network structure in the pellicle. In this case, secretion of cellulose nanofiber was supposed to be the first. References: [1] Seyama, T., et al., Planta, 227: 1187 (2008). [2] Fang, J., et al., Biomacromolecules, in press, DOI: 10.1021/acs.biomac.5b01075

Which was the first to appear, β-1,4 or β-1,3 glucans?

251st National Meeting (2016)

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