Evidence for the Periodically Alternating Microfibrillar Structure of Bacterial Cellulose

Abstract

The microfibrillar structure of bacterial cellulose was investigated. Bacterial cellulose cultured in a jar fermentor was hydrolyzed in 1 N hydrochloric acid for 2 h at 100°C. The residual bacterial cellulose consisted of short strands after hydrolysis. The lengths of 529 short strands on transmission electron micrographs were measured with a ruler, and the length distribution of the short strands was then evaluated by a computer-aided line shape analysis. The length distribution was deconvoluted into five peaks with Gaussian distribution, and the center positions of the peaks occurred at regular intervals. This result demonstrates that the cellulose microfibrils consisted of regularly repeating units of constant length (ca. 0.8μm) and suggests that each unit consisted of an acid hydrolysis-susceptible region (ca. 0.2μm) and an unsusceptible region (ca. 0.6μm).