PHYSICAL AND MECHANICAL PROPERTIES OF BACTERIAL NANOCELLULOSE OBTAINED BY PROLONGED CULTIVATION

A.E. Sitnikova, N.A. Shavyrkina, V.V. Budaeva , A.A. Korchagina, N.V. Bychin
 DOI: 10.25699/SSSB.2021.36.2.014 Download PDF
Abstract: Bacterial nanocellulose (BNC) has unique physical and mechanical properties, as a result of which it has a huge applied potential. The aim of this work was to study the physical and mechanical properties of BNC samples synthesized by the producer of Medusomyces gisevii Sa-12 on a semi-synthetic nutrient medium by the method of prolonged cultivation. BNTs samples were air dried. The article presents data on the study of the properties of BNC obtained in containers of various volumes and made of different materials: in a small-volume container of 0.25 L (experiment No. 1, plastic container, filling 0.20 L), in a container with a volume of 45 L (experiment No. 2, enameled vessel, filling 8 L) and in a container with a volume of 17.3 L (experiment No. 3, glass container, filling 8 L). This method involves multiple weaning of BNC gel films from the same nutrient medium without additional addition of inoculum and nutrients: five times in experiment No. 1, seven times in experiment No. 2, eleven times in experiment No. 3. It was found that the greatest thickness of BNC samples is observed on the 6th day of cultivation in experiment No. 1 – 0.020 mm; on the 10th day in experiment No. 2 – 0.020 mm; on the 4th and 7th days of cultivation in experiment No. 3 – 0.013 mm. The maximum tensile strength for samples of experimental series No. 1 was 84 MPa (II weaning BNTs, 6th day of cultivation), for series No. 2 – 177 MPa (III weaning of BNC, 10th day of cultivation), in experiment No. 3 – 265 MPa (VII weaning BNC, 32-day cultivation). The highest values of the degree of polymerization were recorded in experiments No. 2 and No. 3 (5550), which is 1.5 times more than in experiment No. 1 (3750). Young’s modulus of BNC specimens in experiment No. 1 (1403 MPa) is 3.9 times less than Young’s modulus of specimens obtained in experiment No. 2 (5433 MPa) and 5.2 times less than Young’s modulus of specimens obtained in experiment No. 3 (7250 MPa). The lack of literature data on prolonged cultivation of BNC does not allow us to compare the results obtained, but justifies the undoubted priority of the studies performed.
Index terms: bacterial nanocellulose, Young’s modulus, thickness, tensile strength, degree of polymerization.

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