XRD and solid state 13C-NMR evaluation of the crystallinity enhancement of 13C-labeled bacterial cellulose biosynthesized by Komagataeibacter xylinus under different stimuli: A comparative strategy of analyses

• Published in: Carbohydrate research 2018-05, Vol.461, p.51-59
• Main Authors: Meza-Contreras, Juan C., Manriquez-Gonzalez, Ricardo, Gutiérrez-Ortega, José A., Gonzalez-Garcia, Yolanda
• Format: Article
• Language: English
• Subjects: Allomorphs; Bacterial cellulose; Crystalline phase; Crystallite size; Komagataeibacter xylinus
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2018.03.005

The production and crystallinity of 13C bacterial cellulose (BC) was examined in static culture of Komagataeibacter xylinus with different chemical and physical stimuli: the addition of NaCl or cloramphenicol as well as exposure to a magnetic field or to UV light. Crystalline BC biosynthesized under each stimulus was studied by XRD and solid state 13C NMR analyses. All treatments produced BC with enhanced crystallinity over 90% (XRD) and 80% (NMR) compared to the control (83 and 76%, respectively) or to Avicel (77 and 62%, respectively). The XRD data indicated that the crystallite size was 80–85 Å. Furthermore, changes on the allomorphs (Iα and Iβ) ratio tendency of BC samples addressed to the stimuli were estimated using the C4 signal from 13C NMR data. These results showed a decrease of the allomorph Iα (3%) when BC was biosynthesized with UV light and chloramphenicol compared to control (58.79%). In contrast, the BC obtained with NaCl increased up to 60.31% of the Iα allomorph ratio. [Display omitted] •Enhanced crystallinity of 13C-bacterial cellulose (BC) under different stimuli was achieved.•Changes on the BC crystallinity addressed to the stimuli were evaluated by XRD and NMR.•BC crystallinity enhancement was mostly associated with increased crystallite size.•A simple method by NMR to evaluate changes in Iα and Iβ in the crystalline phase of BC was described.