Morphological Features of the Fibrillar Structure of Plant and Bacterial Cellulose

The authors made a comparison of the micromorphological structure and obtained a statistically significant size distribution of plant and bacterial cellulose microfibrils. Morphological features of the microfibrils structure were studied using a SEM Sigma VP ZEISS scanning electron microscope and an ACM Multimod 8 Bruker atomic-force microscope. The image informativity of the least degree of the microfibrils deformation was achieved by cleaving of the timber sample, which detected the individual fibrils or their bundles. We applied the hemicellulose hydrolysis by briefly heating the wood in the water up to temperature of 235 degrees C to disclose the ligno-hemicellulosic matrix, distorting the image of wood microfibrils in the pictures. Bacterial cellulose images were obtained without a prior sample preparation. The cross-sectional dimensions of microfibrils did not depend on the cell wall layer, where they were localized, and were virtually the same for woody and herbaceous annual plants (with a mean of 27 nm for juniper). The cross-sectional size of microfibrils of bacterial cellulose was 34 nm at an average without a strict orientation of elements of the supra-molecular structure. It was also typical for one of the main structural parts of the plant cell wall - a primary wall. The bimodal nature of the size distribution curve of bacterial cellulose microfibrils demonstrated the microfibrils ability to the parallel placing. Taking into consideration the statistically close size distribution of cellulose microfibrils of plant and bacterial origin, and a similar crystal structure of the samples, we can assume the presence of identical stages of biosynthesis of the S-2 layer in plants and bacterial cellulose.