Biosynthesis of Bacterial Nanocellulose from Low-Cost Cellulosic Feedstocks: Effect of Microbial Producer

Abstract

Biodegradable bacterial nanocellulose (BNC) is a highly in-demand but expensive polymer, and the reduction of its production cost is an important task. The present study aimed to biosynthesize BNC on biologically high-quality hydrolyzate media prepared from miscanthus and oat hulls, and to explore the properties of the resultant BNC depending on the microbial producer used. In this study, three microbial producers were utilized for the biosynthesis of BNC: individual strains Komagataeibacter xylinus B-12429 and Komagataeibacter xylinus B-12431, and symbiotic Medusomyces gisevii Sa-12. The use of symbiotic Medusomyces gisevii Sa-12 was found to have technological benefits: nutrient media require no mineral salts or growth factors, and pasteurization is sufficient for the nutrient medium instead of sterilization. The yield of BNCs produced by the symbiotic culture turned out to be 44–65% higher than that for the individual strains. The physicochemical properties of BNC, such as nanofibril width, degree of polymerization, elastic modulus, Iα allomorph content and crystallinity index, are most notably dependent on the microbial producer type rather than the nutrient medium composition. This is the first study in which we investigated the biosynthesis of BNC on hydrolyzate media prepared from miscanthus and oat hulls under the same conditions but using different microbial producers, and showed that it is advisable to use the symbiotic culture. The choice of a microbial producer is grounded on the yield, production process simplification and properties. The BNC production from technical raw materials would cover considerable demands of BNC for technical purposes without competing with food resources.