Structural Features of Bacterial Nanocellulose Synthesized on Enzymatic Hydrolyzates of Miscanthus × giganteus

Bacterial nanocellulose (BNC) is a promising polysaccharide whose properties depend on the supramolecular structure of its crystalline component. The search for cost-effective alternative nutrient media for BNC production requires a deep understanding of how their composition affects the structure. This study aimed to investigate the structural features of BNC synthesized by the symbiotic culture SCOBY on enzymatic hydrolyzates prepared from chemically treated Miscanthus × giganteus (cv. KAMIS) in comparison with BNC synthesized on a control medium. The study methodology relies on X-ray diffraction analysis performed in reflection and transmission geometries using a full-profile analysis (the Rietveld method) to determine the unit cell parameters and angles, coherent scattering domain (CSD) sizes, and degree of crystallinity (DC). The main results showed that all five BNC samples were identified as Iα cellulose with a content of 95–100% and identical unit cell parameters. The CSD sizes in the reflection and transmission geometries varied in the range of 4.0–7.7 nm, and the longitudinal size was between 12.1 and 18.1 nm. The BNC samples obtained on hydrolyzates exhibited a higher DC (85, 83, 82 and 84%) compared with BNC synthesized on the control medium (78%). It was established that the crystallites of the five BNC samples exhibit anisotropy: the T/R ratio varied from 0.76 to 1.46, depending on the crystallographic direction. The scientific novelty of this work lies in the results of a comprehensive systematic study of the structural features of BNC samples synthesized on miscanthus enzymatic hydrolyzates. It was shown for the first time that replacing the control medium with hydrolyzates improves the BNC quality, which in turn enhances the practical significance of alternative nutrient media. The topic of the cost reduction in the nutrient medium for BNC biosynthesis remains debatable, but this direction aligns with the global trend.