X-ray Diffraction Study of Bacterial Nanocellulose Produced by Medusomyces Gisevii Sa-12 Cultured in Enzymatic Hydrolysa
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CTURE OF MACROMOLECULAR COMPOUNDS
X-ray Diffraction Study of Bacterial Nanocellulose Produced by Medusomyces Gisevii Sa-12 Cultured in Enzymatic Hydrolysates of Miscanthus L. A. Aleshinaa,*, E. K. Gladyshevab, V. V. Budaevab,**, D. S. Golubevb,c, E. A. Skibab, and G. V. Sakovichb aPetrozavodsk
State University, Petrozavodsk, 185910 Russia Institute for Problems of Chemical and Energetic Technologies, Siberian Branch of the Russian Academy of Sciences, Biysk, 659322 Russia c Biysk Technological Institute, Polzunov Altai State Technical University, Biysk, 656038 Russia *e-mail: [email protected] **e-mail: [email protected] b
Received January 30, 2019; revised January 30, 2019; accepted February 25, 2019
Abstract—Bacterial nanocellulose, which was produced by Medusomyces gisevii Sa-12 cultured in enzymatic hydrolysates of Miscanthus, was studied by X-ray diffraction. The characteristics of the supramolecular structure of the crystalline component of cellulose samples, such as the degree of crystallinity and the size and shape of elementary fibrils, were determined. The atomic structure was compared with the known structural models of cellulose, and the synthesized bacterial nanocellulose was shown to be cellulose Iα. The lengths and angles of the triclinic unit cell were determined. The composition of the culture medium made from enzymatic hydrolysates of Miscanthus was found to have an effect on the shape and size of elementary fibrils and have no effect on the degree of crystallinity and the fraction of cellulose allomorph Іα. The use of Medusomyces gisevii Sa-12 as the producing organism allows the preparation of bacterial nanocellulose with a high degree of crystallinity in the range of 86–93% containing cellulose allomorph Іα as the major component. DOI: 10.1134/S1063774519060026
INTRODUCTION The crystallinity index of cellulose and the ratio of the crystalline polymorphs Іα and Іβ in natural cellulose depend on the origin of cellulose (the nature of the producing organism), its subsequent processing, the degree of polymerization, intrachain hydrogen bonding between neighboring monomers of a single polymer chain, and interchain hydrogen bonding between adjacent biopolymer chains [1–3]. Bacterial nanocellulose (BNC) secreted by various bacteria of the genera Acetobacter, Acanthamoeba, and Achromobacter spp. differs from plant cellulose by high purity, an ultrathin structure of microfibrils with a high degree of crystallinity, and the presence of uniformly distributed water, forming stable hydrogels during biosynthesis. Like plant cellulose, BNC belongs to cellulose І, which contains two cellobiose moieties in a parallel (or antiparallel) arrangement per unit cell, but BNC contains allomorph Іα as the major component, as opposed to plant cellulose [1, 4]. Increasing demands for BNC in different fields of industry [5] have stimulated researchers all over the
world to develop new approaches to reducing the cost of the culture medium by replacing the synthetic medium for the BNC biosynthesis with hydrolysates of low-c
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